Date: Mon, 18 Jul 2016 06:57:24 +0000 (UTC) From: Andriy Gapon <avg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-vendor@freebsd.org Subject: svn commit: r302991 - vendor-sys/illumos/dist/uts/common/fs/zfs vendor-sys/illumos/dist/uts/common/fs/zfs/sys vendor/illumos/dist/cmd/zdb vendor/illumos/dist/cmd/ztest Message-ID: <201607180657.u6I6vOxT008306@repo.freebsd.org>
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Author: avg Date: Mon Jul 18 06:57:24 2016 New Revision: 302991 URL: https://svnweb.freebsd.org/changeset/base/302991 Log: 6950 ARC should cache compressed data illumos/illumos-gate@dcbf3bd6a1f1360fc1afcee9e22c6dcff7844bf2 https://github.com/illumos/illumos-gate/commit/dcbf3bd6a1f1360fc1afcee9e22c6dcff7844bf2 https://www.illumos.org/issues/6950 When reading compressed data from disk, the ARC should keep the compressed block cached and only decompress it when consumers access the block. The uncompressed data should be short-lived allowing the ARC to cache a much larger amount of data. The DMU would also maintain a smaller cache of uncompressed blocks to minimize the impact of decompressing frequently accessed blocks. Reviewed by: Prakash Surya <prakash.surya@delphix.com> Reviewed by: Dan Kimmel <dan.kimmel@delphix.com> Reviewed by: Matt Ahrens <mahrens@delphix.com> Reviewed by: Paul Dagnelie <pcd@delphix.com> Reviewed by: Don Brady <don.brady@intel.com> Reviewed by: Richard Elling <Richard.Elling@RichardElling.com> Approved by: Richard Lowe <richlowe@richlowe.net> Author: George Wilson <george.wilson@delphix.com> Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/arc.c vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c vendor-sys/illumos/dist/uts/common/fs/zfs/dmu.c vendor-sys/illumos/dist/uts/common/fs/zfs/dmu_diff.c vendor-sys/illumos/dist/uts/common/fs/zfs/dmu_objset.c vendor-sys/illumos/dist/uts/common/fs/zfs/dmu_send.c vendor-sys/illumos/dist/uts/common/fs/zfs/dmu_traverse.c vendor-sys/illumos/dist/uts/common/fs/zfs/dnode.c vendor-sys/illumos/dist/uts/common/fs/zfs/dnode_sync.c vendor-sys/illumos/dist/uts/common/fs/zfs/dsl_scan.c vendor-sys/illumos/dist/uts/common/fs/zfs/refcount.c vendor-sys/illumos/dist/uts/common/fs/zfs/sys/arc.h vendor-sys/illumos/dist/uts/common/fs/zfs/sys/dbuf.h vendor-sys/illumos/dist/uts/common/fs/zfs/sys/refcount.h vendor-sys/illumos/dist/uts/common/fs/zfs/sys/spa.h vendor-sys/illumos/dist/uts/common/fs/zfs/sys/zio.h vendor-sys/illumos/dist/uts/common/fs/zfs/sys/zio_checksum.h vendor-sys/illumos/dist/uts/common/fs/zfs/zil.c vendor-sys/illumos/dist/uts/common/fs/zfs/zio.c vendor-sys/illumos/dist/uts/common/fs/zfs/zio_checksum.c Changes in other areas also in this revision: Modified: vendor/illumos/dist/cmd/zdb/zdb.c vendor/illumos/dist/cmd/ztest/ztest.c Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/arc.c ============================================================================== --- vendor-sys/illumos/dist/uts/common/fs/zfs/arc.c Mon Jul 18 06:47:08 2016 (r302990) +++ vendor-sys/illumos/dist/uts/common/fs/zfs/arc.c Mon Jul 18 06:57:24 2016 (r302991) @@ -120,9 +120,134 @@ * - ARC header release, as it removes from L2ARC buflists */ +/* + * ARC operation: + * + * Every block that is in the ARC is tracked by an arc_buf_hdr_t structure. + * This structure can point either to a block that is still in the cache or to + * one that is only accessible in an L2 ARC device, or it can provide + * information about a block that was recently evicted. If a block is + * only accessible in the L2ARC, then the arc_buf_hdr_t only has enough + * information to retrieve it from the L2ARC device. This information is + * stored in the l2arc_buf_hdr_t sub-structure of the arc_buf_hdr_t. A block + * that is in this state cannot access the data directly. + * + * Blocks that are actively being referenced or have not been evicted + * are cached in the L1ARC. The L1ARC (l1arc_buf_hdr_t) is a structure within + * the arc_buf_hdr_t that will point to the data block in memory. A block can + * only be read by a consumer if it has an l1arc_buf_hdr_t. The L1ARC + * caches data in two ways -- in a list of arc buffers (arc_buf_t) and + * also in the arc_buf_hdr_t's private physical data block pointer (b_pdata). + * Each arc buffer (arc_buf_t) is being actively accessed by a specific ARC + * consumer, and always contains uncompressed data. The ARC will provide + * references to this data and will keep it cached until it is no longer in + * use. Typically, the arc will try to cache only the L1ARC's physical data + * block and will aggressively evict any arc_buf_t that is no longer referenced. + * The amount of memory consumed by the arc_buf_t's can be seen via the + * "overhead_size" kstat. + * + * + * arc_buf_hdr_t + * +-----------+ + * | | + * | | + * | | + * +-----------+ + * l2arc_buf_hdr_t| | + * | | + * +-----------+ + * l1arc_buf_hdr_t| | + * | | arc_buf_t + * | b_buf +------------>+---------+ arc_buf_t + * | | |b_next +---->+---------+ + * | b_pdata +-+ |---------| |b_next +-->NULL + * +-----------+ | | | +---------+ + * | |b_data +-+ | | + * | +---------+ | |b_data +-+ + * +->+------+ | +---------+ | + * (potentially) | | | | + * compressed | | | | + * data +------+ | v + * +->+------+ +------+ + * uncompressed | | | | + * data | | | | + * +------+ +------+ + * + * The L1ARC's data pointer, however, may or may not be uncompressed. The + * ARC has the ability to store the physical data (b_pdata) associated with + * the DVA of the arc_buf_hdr_t. Since the b_pdata is a copy of the on-disk + * physical block, it will match its on-disk compression characteristics. + * If the block on-disk is compressed, then the physical data block + * in the cache will also be compressed and vice-versa. This behavior + * can be disabled by setting 'zfs_compressed_arc_enabled' to B_FALSE. When the + * compressed ARC functionality is disabled, the b_pdata will point to an + * uncompressed version of the on-disk data. + * + * When a consumer reads a block, the ARC must first look to see if the + * arc_buf_hdr_t is cached. If the hdr is cached and already has an arc_buf_t, + * then an additional arc_buf_t is allocated and the uncompressed data is + * bcopied from the existing arc_buf_t. If the hdr is cached but does not + * have an arc_buf_t, then the ARC allocates a new arc_buf_t and decompresses + * the b_pdata contents into the arc_buf_t's b_data. If the arc_buf_hdr_t's + * b_pdata is not compressed, then the block is shared with the newly + * allocated arc_buf_t. This block sharing only occurs with one arc_buf_t + * in the arc buffer chain. Sharing the block reduces the memory overhead + * required when the hdr is caching uncompressed blocks or the compressed + * arc functionality has been disabled via 'zfs_compressed_arc_enabled'. + * + * The diagram below shows an example of an uncompressed ARC hdr that is + * sharing its data with an arc_buf_t: + * + * arc_buf_hdr_t + * +-----------+ + * | | + * | | + * | | + * +-----------+ + * l2arc_buf_hdr_t| | + * | | + * +-----------+ + * l1arc_buf_hdr_t| | + * | | arc_buf_t (shared) + * | b_buf +------------>+---------+ arc_buf_t + * | | |b_next +---->+---------+ + * | b_pdata +-+ |---------| |b_next +-->NULL + * +-----------+ | | | +---------+ + * | |b_data +-+ | | + * | +---------+ | |b_data +-+ + * +->+------+ | +---------+ | + * | | | | + * uncompressed | | | | + * data +------+ | | + * ^ +->+------+ | + * | uncompressed | | | + * | data | | | + * | +------+ | + * +---------------------------------+ + * + * Writing to the arc requires that the ARC first discard the b_pdata + * since the physical block is about to be rewritten. The new data contents + * will be contained in the arc_buf_t (uncompressed). As the I/O pipeline + * performs the write, it may compress the data before writing it to disk. + * The ARC will be called with the transformed data and will bcopy the + * transformed on-disk block into a newly allocated b_pdata. + * + * When the L2ARC is in use, it will also take advantage of the b_pdata. The + * L2ARC will always write the contents of b_pdata to the L2ARC. This means + * that when compressed arc is enabled that the L2ARC blocks are identical + * to the on-disk block in the main data pool. This provides a significant + * advantage since the ARC can leverage the bp's checksum when reading from the + * L2ARC to determine if the contents are valid. However, if the compressed + * arc is disabled, then the L2ARC's block must be transformed to look + * like the physical block in the main data pool before comparing the + * checksum and determining its validity. + */ + #include <sys/spa.h> #include <sys/zio.h> +#include <sys/spa_impl.h> #include <sys/zio_compress.h> +#include <sys/zio_checksum.h> #include <sys/zfs_context.h> #include <sys/arc.h> #include <sys/refcount.h> @@ -151,10 +276,6 @@ static kcondvar_t arc_reclaim_thread_cv; static boolean_t arc_reclaim_thread_exit; static kcondvar_t arc_reclaim_waiters_cv; -static kmutex_t arc_user_evicts_lock; -static kcondvar_t arc_user_evicts_cv; -static boolean_t arc_user_evicts_thread_exit; - uint_t arc_reduce_dnlc_percent = 3; /* @@ -230,9 +351,10 @@ uint64_t zfs_arc_meta_min = 0; int zfs_arc_grow_retry = 0; int zfs_arc_shrink_shift = 0; int zfs_arc_p_min_shift = 0; -int zfs_disable_dup_eviction = 0; int zfs_arc_average_blocksize = 8 * 1024; /* 8KB */ +boolean_t zfs_compressed_arc_enabled = B_TRUE; + /* * Note that buffers can be in one of 6 states: * ARC_anon - anonymous (discussed below) @@ -273,7 +395,7 @@ typedef struct arc_state { /* * total amount of evictable data in this state */ - uint64_t arcs_lsize[ARC_BUFC_NUMTYPES]; + refcount_t arcs_esize[ARC_BUFC_NUMTYPES]; /* * total amount of data in this state; this includes: evictable, * non-evictable, ARC_BUFC_DATA, and ARC_BUFC_METADATA. @@ -338,6 +460,26 @@ typedef struct arc_stats { kstat_named_t arcstat_c_max; kstat_named_t arcstat_size; /* + * Number of compressed bytes stored in the arc_buf_hdr_t's b_pdata. + * Note that the compressed bytes may match the uncompressed bytes + * if the block is either not compressed or compressed arc is disabled. + */ + kstat_named_t arcstat_compressed_size; + /* + * Uncompressed size of the data stored in b_pdata. If compressed + * arc is disabled then this value will be identical to the stat + * above. + */ + kstat_named_t arcstat_uncompressed_size; + /* + * Number of bytes stored in all the arc_buf_t's. This is classified + * as "overhead" since this data is typically short-lived and will + * be evicted from the arc when it becomes unreferenced unless the + * zfs_keep_uncompressed_metadata or zfs_keep_uncompressed_level + * values have been set (see comment in dbuf.c for more information). + */ + kstat_named_t arcstat_overhead_size; + /* * Number of bytes consumed by internal ARC structures necessary * for tracking purposes; these structures are not actually * backed by ARC buffers. This includes arc_buf_hdr_t structures @@ -482,20 +624,13 @@ typedef struct arc_stats { kstat_named_t arcstat_l2_evict_reading; kstat_named_t arcstat_l2_evict_l1cached; kstat_named_t arcstat_l2_free_on_write; - kstat_named_t arcstat_l2_cdata_free_on_write; kstat_named_t arcstat_l2_abort_lowmem; kstat_named_t arcstat_l2_cksum_bad; kstat_named_t arcstat_l2_io_error; kstat_named_t arcstat_l2_size; kstat_named_t arcstat_l2_asize; kstat_named_t arcstat_l2_hdr_size; - kstat_named_t arcstat_l2_compress_successes; - kstat_named_t arcstat_l2_compress_zeros; - kstat_named_t arcstat_l2_compress_failures; kstat_named_t arcstat_memory_throttle_count; - kstat_named_t arcstat_duplicate_buffers; - kstat_named_t arcstat_duplicate_buffers_size; - kstat_named_t arcstat_duplicate_reads; kstat_named_t arcstat_meta_used; kstat_named_t arcstat_meta_limit; kstat_named_t arcstat_meta_max; @@ -537,6 +672,9 @@ static arc_stats_t arc_stats = { { "c_min", KSTAT_DATA_UINT64 }, { "c_max", KSTAT_DATA_UINT64 }, { "size", KSTAT_DATA_UINT64 }, + { "compressed_size", KSTAT_DATA_UINT64 }, + { "uncompressed_size", KSTAT_DATA_UINT64 }, + { "overhead_size", KSTAT_DATA_UINT64 }, { "hdr_size", KSTAT_DATA_UINT64 }, { "data_size", KSTAT_DATA_UINT64 }, { "metadata_size", KSTAT_DATA_UINT64 }, @@ -570,20 +708,13 @@ static arc_stats_t arc_stats = { { "l2_evict_reading", KSTAT_DATA_UINT64 }, { "l2_evict_l1cached", KSTAT_DATA_UINT64 }, { "l2_free_on_write", KSTAT_DATA_UINT64 }, - { "l2_cdata_free_on_write", KSTAT_DATA_UINT64 }, { "l2_abort_lowmem", KSTAT_DATA_UINT64 }, { "l2_cksum_bad", KSTAT_DATA_UINT64 }, { "l2_io_error", KSTAT_DATA_UINT64 }, { "l2_size", KSTAT_DATA_UINT64 }, { "l2_asize", KSTAT_DATA_UINT64 }, { "l2_hdr_size", KSTAT_DATA_UINT64 }, - { "l2_compress_successes", KSTAT_DATA_UINT64 }, - { "l2_compress_zeros", KSTAT_DATA_UINT64 }, - { "l2_compress_failures", KSTAT_DATA_UINT64 }, { "memory_throttle_count", KSTAT_DATA_UINT64 }, - { "duplicate_buffers", KSTAT_DATA_UINT64 }, - { "duplicate_buffers_size", KSTAT_DATA_UINT64 }, - { "duplicate_reads", KSTAT_DATA_UINT64 }, { "arc_meta_used", KSTAT_DATA_UINT64 }, { "arc_meta_limit", KSTAT_DATA_UINT64 }, { "arc_meta_max", KSTAT_DATA_UINT64 }, @@ -656,8 +787,12 @@ static arc_state_t *arc_l2c_only; #define arc_meta_used ARCSTAT(arcstat_meta_used) /* size of metadata */ #define arc_meta_max ARCSTAT(arcstat_meta_max) /* max size of metadata */ -#define L2ARC_IS_VALID_COMPRESS(_c_) \ - ((_c_) == ZIO_COMPRESS_LZ4 || (_c_) == ZIO_COMPRESS_EMPTY) +/* compressed size of entire arc */ +#define arc_compressed_size ARCSTAT(arcstat_compressed_size) +/* uncompressed size of entire arc */ +#define arc_uncompressed_size ARCSTAT(arcstat_uncompressed_size) +/* number of bytes in the arc from arc_buf_t's */ +#define arc_overhead_size ARCSTAT(arcstat_overhead_size) static int arc_no_grow; /* Don't try to grow cache size */ static uint64_t arc_tempreserve; @@ -717,6 +852,7 @@ struct arc_write_callback { */ typedef struct l1arc_buf_hdr { kmutex_t b_freeze_lock; + zio_cksum_t *b_freeze_cksum; #ifdef ZFS_DEBUG /* * used for debugging wtih kmem_flags - by allocating and freeing @@ -727,9 +863,10 @@ typedef struct l1arc_buf_hdr { #endif arc_buf_t *b_buf; - uint32_t b_datacnt; + uint32_t b_bufcnt; /* for waiting on writes to complete */ kcondvar_t b_cv; + uint8_t b_byteswap; /* protected by arc state mutex */ arc_state_t *b_state; @@ -742,8 +879,7 @@ typedef struct l1arc_buf_hdr { refcount_t b_refcnt; arc_callback_t *b_acb; - /* temporary buffer holder for in-flight compressed data */ - void *b_tmp_cdata; + void *b_pdata; } l1arc_buf_hdr_t; typedef struct l2arc_dev l2arc_dev_t; @@ -752,9 +888,6 @@ typedef struct l2arc_buf_hdr { /* protected by arc_buf_hdr mutex */ l2arc_dev_t *b_dev; /* L2ARC device */ uint64_t b_daddr; /* disk address, offset byte */ - /* real alloc'd buffer size depending on b_compress applied */ - int32_t b_asize; - uint8_t b_compress; list_node_t b_l2node; } l2arc_buf_hdr_t; @@ -763,20 +896,37 @@ struct arc_buf_hdr { /* protected by hash lock */ dva_t b_dva; uint64_t b_birth; - /* - * Even though this checksum is only set/verified when a buffer is in - * the L1 cache, it needs to be in the set of common fields because it - * must be preserved from the time before a buffer is written out to - * L2ARC until after it is read back in. - */ - zio_cksum_t *b_freeze_cksum; + arc_buf_contents_t b_type; arc_buf_hdr_t *b_hash_next; arc_flags_t b_flags; - /* immutable */ - int32_t b_size; - uint64_t b_spa; + /* + * This field stores the size of the data buffer after + * compression, and is set in the arc's zio completion handlers. + * It is in units of SPA_MINBLOCKSIZE (e.g. 1 == 512 bytes). + * + * While the block pointers can store up to 32MB in their psize + * field, we can only store up to 32MB minus 512B. This is due + * to the bp using a bias of 1, whereas we use a bias of 0 (i.e. + * a field of zeros represents 512B in the bp). We can't use a + * bias of 1 since we need to reserve a psize of zero, here, to + * represent holes and embedded blocks. + * + * This isn't a problem in practice, since the maximum size of a + * buffer is limited to 16MB, so we never need to store 32MB in + * this field. Even in the upstream illumos code base, the + * maximum size of a buffer is limited to 16MB. + */ + uint16_t b_psize; + + /* + * This field stores the size of the data buffer before + * compression, and cannot change once set. It is in units + * of SPA_MINBLOCKSIZE (e.g. 2 == 1024 bytes) + */ + uint16_t b_lsize; /* immutable */ + uint64_t b_spa; /* immutable */ /* L2ARC fields. Undefined when not in L2ARC. */ l2arc_buf_hdr_t b_l2hdr; @@ -784,9 +934,6 @@ struct arc_buf_hdr { l1arc_buf_hdr_t b_l1hdr; }; -static arc_buf_t *arc_eviction_list; -static arc_buf_hdr_t arc_eviction_hdr; - #define GHOST_STATE(state) \ ((state) == arc_mru_ghost || (state) == arc_mfu_ghost || \ (state) == arc_l2c_only) @@ -795,25 +942,35 @@ static arc_buf_hdr_t arc_eviction_hdr; #define HDR_IO_IN_PROGRESS(hdr) ((hdr)->b_flags & ARC_FLAG_IO_IN_PROGRESS) #define HDR_IO_ERROR(hdr) ((hdr)->b_flags & ARC_FLAG_IO_ERROR) #define HDR_PREFETCH(hdr) ((hdr)->b_flags & ARC_FLAG_PREFETCH) -#define HDR_FREED_IN_READ(hdr) ((hdr)->b_flags & ARC_FLAG_FREED_IN_READ) -#define HDR_BUF_AVAILABLE(hdr) ((hdr)->b_flags & ARC_FLAG_BUF_AVAILABLE) +#define HDR_COMPRESSION_ENABLED(hdr) \ + ((hdr)->b_flags & ARC_FLAG_COMPRESSED_ARC) #define HDR_L2CACHE(hdr) ((hdr)->b_flags & ARC_FLAG_L2CACHE) -#define HDR_L2COMPRESS(hdr) ((hdr)->b_flags & ARC_FLAG_L2COMPRESS) #define HDR_L2_READING(hdr) \ - (((hdr)->b_flags & ARC_FLAG_IO_IN_PROGRESS) && \ - ((hdr)->b_flags & ARC_FLAG_HAS_L2HDR)) + (((hdr)->b_flags & ARC_FLAG_IO_IN_PROGRESS) && \ + ((hdr)->b_flags & ARC_FLAG_HAS_L2HDR)) #define HDR_L2_WRITING(hdr) ((hdr)->b_flags & ARC_FLAG_L2_WRITING) #define HDR_L2_EVICTED(hdr) ((hdr)->b_flags & ARC_FLAG_L2_EVICTED) #define HDR_L2_WRITE_HEAD(hdr) ((hdr)->b_flags & ARC_FLAG_L2_WRITE_HEAD) +#define HDR_SHARED_DATA(hdr) ((hdr)->b_flags & ARC_FLAG_SHARED_DATA) #define HDR_ISTYPE_METADATA(hdr) \ - ((hdr)->b_flags & ARC_FLAG_BUFC_METADATA) + ((hdr)->b_flags & ARC_FLAG_BUFC_METADATA) #define HDR_ISTYPE_DATA(hdr) (!HDR_ISTYPE_METADATA(hdr)) #define HDR_HAS_L1HDR(hdr) ((hdr)->b_flags & ARC_FLAG_HAS_L1HDR) #define HDR_HAS_L2HDR(hdr) ((hdr)->b_flags & ARC_FLAG_HAS_L2HDR) +/* For storing compression mode in b_flags */ +#define HDR_COMPRESS_OFFSET (highbit64(ARC_FLAG_COMPRESS_0) - 1) + +#define HDR_GET_COMPRESS(hdr) ((enum zio_compress)BF32_GET((hdr)->b_flags, \ + HDR_COMPRESS_OFFSET, SPA_COMPRESSBITS)) +#define HDR_SET_COMPRESS(hdr, cmp) BF32_SET((hdr)->b_flags, \ + HDR_COMPRESS_OFFSET, SPA_COMPRESSBITS, (cmp)); + +#define ARC_BUF_LAST(buf) ((buf)->b_next == NULL) + /* * Other sizes */ @@ -866,16 +1023,6 @@ uint64_t zfs_crc64_table[256]; #define L2ARC_FEED_SECS 1 /* caching interval secs */ #define L2ARC_FEED_MIN_MS 200 /* min caching interval ms */ -/* - * Used to distinguish headers that are being process by - * l2arc_write_buffers(), but have yet to be assigned to a l2arc disk - * address. This can happen when the header is added to the l2arc's list - * of buffers to write in the first stage of l2arc_write_buffers(), but - * has not yet been written out which happens in the second stage of - * l2arc_write_buffers(). - */ -#define L2ARC_ADDR_UNSET ((uint64_t)(-1)) - #define l2arc_writes_sent ARCSTAT(arcstat_l2_writes_sent) #define l2arc_writes_done ARCSTAT(arcstat_l2_writes_done) @@ -917,12 +1064,10 @@ static kmutex_t l2arc_free_on_write_mtx; static uint64_t l2arc_ndev; /* number of devices */ typedef struct l2arc_read_callback { - arc_buf_t *l2rcb_buf; /* read buffer */ - spa_t *l2rcb_spa; /* spa */ + arc_buf_hdr_t *l2rcb_hdr; /* read buffer */ blkptr_t l2rcb_bp; /* original blkptr */ zbookmark_phys_t l2rcb_zb; /* original bookmark */ int l2rcb_flags; /* original flags */ - enum zio_compress l2rcb_compress; /* applied compress */ } l2arc_read_callback_t; typedef struct l2arc_write_callback { @@ -934,7 +1079,7 @@ typedef struct l2arc_data_free { /* protected by l2arc_free_on_write_mtx */ void *l2df_data; size_t l2df_size; - void (*l2df_func)(void *, size_t); + arc_buf_contents_t l2df_type; list_node_t l2df_list_node; } l2arc_data_free_t; @@ -942,21 +1087,22 @@ static kmutex_t l2arc_feed_thr_lock; static kcondvar_t l2arc_feed_thr_cv; static uint8_t l2arc_thread_exit; -static void arc_get_data_buf(arc_buf_t *); +static void *arc_get_data_buf(arc_buf_hdr_t *, uint64_t, void *); +static void arc_free_data_buf(arc_buf_hdr_t *, void *, uint64_t, void *); +static void arc_hdr_free_pdata(arc_buf_hdr_t *hdr); +static void arc_hdr_alloc_pdata(arc_buf_hdr_t *); static void arc_access(arc_buf_hdr_t *, kmutex_t *); static boolean_t arc_is_overflowing(); static void arc_buf_watch(arc_buf_t *); static arc_buf_contents_t arc_buf_type(arc_buf_hdr_t *); static uint32_t arc_bufc_to_flags(arc_buf_contents_t); +static inline void arc_hdr_set_flags(arc_buf_hdr_t *hdr, arc_flags_t flags); +static inline void arc_hdr_clear_flags(arc_buf_hdr_t *hdr, arc_flags_t flags); static boolean_t l2arc_write_eligible(uint64_t, arc_buf_hdr_t *); static void l2arc_read_done(zio_t *); -static boolean_t l2arc_compress_buf(arc_buf_hdr_t *); -static void l2arc_decompress_zio(zio_t *, arc_buf_hdr_t *, enum zio_compress); -static void l2arc_release_cdata_buf(arc_buf_hdr_t *); - static uint64_t buf_hash(uint64_t spa, const dva_t *dva, uint64_t birth) { @@ -974,14 +1120,14 @@ buf_hash(uint64_t spa, const dva_t *dva, return (crc); } -#define BUF_EMPTY(buf) \ - ((buf)->b_dva.dva_word[0] == 0 && \ - (buf)->b_dva.dva_word[1] == 0) - -#define BUF_EQUAL(spa, dva, birth, buf) \ - ((buf)->b_dva.dva_word[0] == (dva)->dva_word[0]) && \ - ((buf)->b_dva.dva_word[1] == (dva)->dva_word[1]) && \ - ((buf)->b_birth == birth) && ((buf)->b_spa == spa) +#define HDR_EMPTY(hdr) \ + ((hdr)->b_dva.dva_word[0] == 0 && \ + (hdr)->b_dva.dva_word[1] == 0) + +#define HDR_EQUAL(spa, dva, birth, hdr) \ + ((hdr)->b_dva.dva_word[0] == (dva)->dva_word[0]) && \ + ((hdr)->b_dva.dva_word[1] == (dva)->dva_word[1]) && \ + ((hdr)->b_birth == birth) && ((hdr)->b_spa == spa) static void buf_discard_identity(arc_buf_hdr_t *hdr) @@ -1003,7 +1149,7 @@ buf_hash_find(uint64_t spa, const blkptr mutex_enter(hash_lock); for (hdr = buf_hash_table.ht_table[idx]; hdr != NULL; hdr = hdr->b_hash_next) { - if (BUF_EQUAL(spa, dva, birth, hdr)) { + if (HDR_EQUAL(spa, dva, birth, hdr)) { *lockp = hash_lock; return (hdr); } @@ -1041,13 +1187,13 @@ buf_hash_insert(arc_buf_hdr_t *hdr, kmut for (fhdr = buf_hash_table.ht_table[idx], i = 0; fhdr != NULL; fhdr = fhdr->b_hash_next, i++) { - if (BUF_EQUAL(hdr->b_spa, &hdr->b_dva, hdr->b_birth, fhdr)) + if (HDR_EQUAL(hdr->b_spa, &hdr->b_dva, hdr->b_birth, fhdr)) return (fhdr); } hdr->b_hash_next = buf_hash_table.ht_table[idx]; buf_hash_table.ht_table[idx] = hdr; - hdr->b_flags |= ARC_FLAG_IN_HASH_TABLE; + arc_hdr_set_flags(hdr, ARC_FLAG_IN_HASH_TABLE); /* collect some hash table performance data */ if (i > 0) { @@ -1075,12 +1221,12 @@ buf_hash_remove(arc_buf_hdr_t *hdr) hdrp = &buf_hash_table.ht_table[idx]; while ((fhdr = *hdrp) != hdr) { - ASSERT(fhdr != NULL); + ASSERT3P(fhdr, !=, NULL); hdrp = &fhdr->b_hash_next; } *hdrp = hdr->b_hash_next; hdr->b_hash_next = NULL; - hdr->b_flags &= ~ARC_FLAG_IN_HASH_TABLE; + arc_hdr_clear_flags(hdr, ARC_FLAG_IN_HASH_TABLE); /* collect some hash table performance data */ ARCSTAT_BUMPDOWN(arcstat_hash_elements); @@ -1166,7 +1312,7 @@ hdr_full_dest(void *vbuf, void *unused) { arc_buf_hdr_t *hdr = vbuf; - ASSERT(BUF_EMPTY(hdr)); + ASSERT(HDR_EMPTY(hdr)); cv_destroy(&hdr->b_l1hdr.b_cv); refcount_destroy(&hdr->b_l1hdr.b_refcnt); mutex_destroy(&hdr->b_l1hdr.b_freeze_lock); @@ -1180,7 +1326,7 @@ hdr_l2only_dest(void *vbuf, void *unused { arc_buf_hdr_t *hdr = vbuf; - ASSERT(BUF_EMPTY(hdr)); + ASSERT(HDR_EMPTY(hdr)); arc_space_return(HDR_L2ONLY_SIZE, ARC_SPACE_L2HDRS); } @@ -1253,166 +1399,138 @@ retry: } } -/* - * Transition between the two allocation states for the arc_buf_hdr struct. - * The arc_buf_hdr struct can be allocated with (hdr_full_cache) or without - * (hdr_l2only_cache) the fields necessary for the L1 cache - the smaller - * version is used when a cache buffer is only in the L2ARC in order to reduce - * memory usage. - */ -static arc_buf_hdr_t * -arc_hdr_realloc(arc_buf_hdr_t *hdr, kmem_cache_t *old, kmem_cache_t *new) -{ - ASSERT(HDR_HAS_L2HDR(hdr)); - - arc_buf_hdr_t *nhdr; - l2arc_dev_t *dev = hdr->b_l2hdr.b_dev; - - ASSERT((old == hdr_full_cache && new == hdr_l2only_cache) || - (old == hdr_l2only_cache && new == hdr_full_cache)); - - nhdr = kmem_cache_alloc(new, KM_PUSHPAGE); - - ASSERT(MUTEX_HELD(HDR_LOCK(hdr))); - buf_hash_remove(hdr); - - bcopy(hdr, nhdr, HDR_L2ONLY_SIZE); - - if (new == hdr_full_cache) { - nhdr->b_flags |= ARC_FLAG_HAS_L1HDR; - /* - * arc_access and arc_change_state need to be aware that a - * header has just come out of L2ARC, so we set its state to - * l2c_only even though it's about to change. - */ - nhdr->b_l1hdr.b_state = arc_l2c_only; - - /* Verify previous threads set to NULL before freeing */ - ASSERT3P(nhdr->b_l1hdr.b_tmp_cdata, ==, NULL); - } else { - ASSERT(hdr->b_l1hdr.b_buf == NULL); - ASSERT0(hdr->b_l1hdr.b_datacnt); - - /* - * If we've reached here, We must have been called from - * arc_evict_hdr(), as such we should have already been - * removed from any ghost list we were previously on - * (which protects us from racing with arc_evict_state), - * thus no locking is needed during this check. - */ - ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node)); - - /* - * A buffer must not be moved into the arc_l2c_only - * state if it's not finished being written out to the - * l2arc device. Otherwise, the b_l1hdr.b_tmp_cdata field - * might try to be accessed, even though it was removed. - */ - VERIFY(!HDR_L2_WRITING(hdr)); - VERIFY3P(hdr->b_l1hdr.b_tmp_cdata, ==, NULL); +#define ARC_MINTIME (hz>>4) /* 62 ms */ -#ifdef ZFS_DEBUG - if (hdr->b_l1hdr.b_thawed != NULL) { - kmem_free(hdr->b_l1hdr.b_thawed, 1); - hdr->b_l1hdr.b_thawed = NULL; - } -#endif +static inline boolean_t +arc_buf_is_shared(arc_buf_t *buf) +{ + boolean_t shared = (buf->b_data != NULL && + buf->b_data == buf->b_hdr->b_l1hdr.b_pdata); + IMPLY(shared, HDR_SHARED_DATA(buf->b_hdr)); + return (shared); +} - nhdr->b_flags &= ~ARC_FLAG_HAS_L1HDR; +static inline void +arc_cksum_free(arc_buf_hdr_t *hdr) +{ + ASSERT(HDR_HAS_L1HDR(hdr)); + mutex_enter(&hdr->b_l1hdr.b_freeze_lock); + if (hdr->b_l1hdr.b_freeze_cksum != NULL) { + kmem_free(hdr->b_l1hdr.b_freeze_cksum, sizeof (zio_cksum_t)); + hdr->b_l1hdr.b_freeze_cksum = NULL; } - /* - * The header has been reallocated so we need to re-insert it into any - * lists it was on. - */ - (void) buf_hash_insert(nhdr, NULL); - - ASSERT(list_link_active(&hdr->b_l2hdr.b_l2node)); - - mutex_enter(&dev->l2ad_mtx); - - /* - * We must place the realloc'ed header back into the list at - * the same spot. Otherwise, if it's placed earlier in the list, - * l2arc_write_buffers() could find it during the function's - * write phase, and try to write it out to the l2arc. - */ - list_insert_after(&dev->l2ad_buflist, hdr, nhdr); - list_remove(&dev->l2ad_buflist, hdr); - - mutex_exit(&dev->l2ad_mtx); - - /* - * Since we're using the pointer address as the tag when - * incrementing and decrementing the l2ad_alloc refcount, we - * must remove the old pointer (that we're about to destroy) and - * add the new pointer to the refcount. Otherwise we'd remove - * the wrong pointer address when calling arc_hdr_destroy() later. - */ - - (void) refcount_remove_many(&dev->l2ad_alloc, - hdr->b_l2hdr.b_asize, hdr); - - (void) refcount_add_many(&dev->l2ad_alloc, - nhdr->b_l2hdr.b_asize, nhdr); - - buf_discard_identity(hdr); - hdr->b_freeze_cksum = NULL; - kmem_cache_free(old, hdr); - - return (nhdr); + mutex_exit(&hdr->b_l1hdr.b_freeze_lock); } - -#define ARC_MINTIME (hz>>4) /* 62 ms */ - static void arc_cksum_verify(arc_buf_t *buf) { + arc_buf_hdr_t *hdr = buf->b_hdr; zio_cksum_t zc; if (!(zfs_flags & ZFS_DEBUG_MODIFY)) return; - mutex_enter(&buf->b_hdr->b_l1hdr.b_freeze_lock); - if (buf->b_hdr->b_freeze_cksum == NULL || HDR_IO_ERROR(buf->b_hdr)) { - mutex_exit(&buf->b_hdr->b_l1hdr.b_freeze_lock); + ASSERT(HDR_HAS_L1HDR(hdr)); + + mutex_enter(&hdr->b_l1hdr.b_freeze_lock); + if (hdr->b_l1hdr.b_freeze_cksum == NULL || HDR_IO_ERROR(hdr)) { + mutex_exit(&hdr->b_l1hdr.b_freeze_lock); return; } - fletcher_2_native(buf->b_data, buf->b_hdr->b_size, NULL, &zc); - if (!ZIO_CHECKSUM_EQUAL(*buf->b_hdr->b_freeze_cksum, zc)) + fletcher_2_native(buf->b_data, HDR_GET_LSIZE(hdr), NULL, &zc); + if (!ZIO_CHECKSUM_EQUAL(*hdr->b_l1hdr.b_freeze_cksum, zc)) panic("buffer modified while frozen!"); - mutex_exit(&buf->b_hdr->b_l1hdr.b_freeze_lock); + mutex_exit(&hdr->b_l1hdr.b_freeze_lock); } -static int -arc_cksum_equal(arc_buf_t *buf) +static boolean_t +arc_cksum_is_equal(arc_buf_hdr_t *hdr, zio_t *zio) { - zio_cksum_t zc; - int equal; + enum zio_compress compress = BP_GET_COMPRESS(zio->io_bp); + boolean_t valid_cksum; - mutex_enter(&buf->b_hdr->b_l1hdr.b_freeze_lock); - fletcher_2_native(buf->b_data, buf->b_hdr->b_size, NULL, &zc); - equal = ZIO_CHECKSUM_EQUAL(*buf->b_hdr->b_freeze_cksum, zc); - mutex_exit(&buf->b_hdr->b_l1hdr.b_freeze_lock); + ASSERT(!BP_IS_EMBEDDED(zio->io_bp)); + VERIFY3U(BP_GET_PSIZE(zio->io_bp), ==, HDR_GET_PSIZE(hdr)); + + /* + * We rely on the blkptr's checksum to determine if the block + * is valid or not. When compressed arc is enabled, the l2arc + * writes the block to the l2arc just as it appears in the pool. + * This allows us to use the blkptr's checksum to validate the + * data that we just read off of the l2arc without having to store + * a separate checksum in the arc_buf_hdr_t. However, if compressed + * arc is disabled, then the data written to the l2arc is always + * uncompressed and won't match the block as it exists in the main + * pool. When this is the case, we must first compress it if it is + * compressed on the main pool before we can validate the checksum. + */ + if (!HDR_COMPRESSION_ENABLED(hdr) && compress != ZIO_COMPRESS_OFF) { + ASSERT3U(HDR_GET_COMPRESS(hdr), ==, ZIO_COMPRESS_OFF); + uint64_t lsize = HDR_GET_LSIZE(hdr); + uint64_t csize; + + void *cbuf = zio_buf_alloc(HDR_GET_PSIZE(hdr)); + csize = zio_compress_data(compress, zio->io_data, cbuf, lsize); + ASSERT3U(csize, <=, HDR_GET_PSIZE(hdr)); + if (csize < HDR_GET_PSIZE(hdr)) { + /* + * Compressed blocks are always a multiple of the + * smallest ashift in the pool. Ideally, we would + * like to round up the csize to the next + * spa_min_ashift but that value may have changed + * since the block was last written. Instead, + * we rely on the fact that the hdr's psize + * was set to the psize of the block when it was + * last written. We set the csize to that value + * and zero out any part that should not contain + * data. + */ + bzero((char *)cbuf + csize, HDR_GET_PSIZE(hdr) - csize); + csize = HDR_GET_PSIZE(hdr); + } + zio_push_transform(zio, cbuf, csize, HDR_GET_PSIZE(hdr), NULL); + } - return (equal); + /* + * Block pointers always store the checksum for the logical data. + * If the block pointer has the gang bit set, then the checksum + * it represents is for the reconstituted data and not for an + * individual gang member. The zio pipeline, however, must be able to + * determine the checksum of each of the gang constituents so it + * treats the checksum comparison differently than what we need + * for l2arc blocks. This prevents us from using the + * zio_checksum_error() interface directly. Instead we must call the + * zio_checksum_error_impl() so that we can ensure the checksum is + * generated using the correct checksum algorithm and accounts for the + * logical I/O size and not just a gang fragment. + */ + valid_cksum = (zio_checksum_error_impl(zio->io_spa, zio->io_bp, + BP_GET_CHECKSUM(zio->io_bp), zio->io_data, zio->io_size, + zio->io_offset, NULL) == 0); + zio_pop_transforms(zio); + return (valid_cksum); } static void -arc_cksum_compute(arc_buf_t *buf, boolean_t force) +arc_cksum_compute(arc_buf_t *buf) { - if (!force && !(zfs_flags & ZFS_DEBUG_MODIFY)) + arc_buf_hdr_t *hdr = buf->b_hdr; + + if (!(zfs_flags & ZFS_DEBUG_MODIFY)) return; + ASSERT(HDR_HAS_L1HDR(hdr)); mutex_enter(&buf->b_hdr->b_l1hdr.b_freeze_lock); - if (buf->b_hdr->b_freeze_cksum != NULL) { - mutex_exit(&buf->b_hdr->b_l1hdr.b_freeze_lock); + if (hdr->b_l1hdr.b_freeze_cksum != NULL) { + mutex_exit(&hdr->b_l1hdr.b_freeze_lock); return; } - buf->b_hdr->b_freeze_cksum = kmem_alloc(sizeof (zio_cksum_t), KM_SLEEP); - fletcher_2_native(buf->b_data, buf->b_hdr->b_size, - NULL, buf->b_hdr->b_freeze_cksum); - mutex_exit(&buf->b_hdr->b_l1hdr.b_freeze_lock); + hdr->b_l1hdr.b_freeze_cksum = kmem_alloc(sizeof (zio_cksum_t), + KM_SLEEP); + fletcher_2_native(buf->b_data, HDR_GET_LSIZE(hdr), NULL, + hdr->b_l1hdr.b_freeze_cksum); + mutex_exit(&hdr->b_l1hdr.b_freeze_lock); arc_buf_watch(buf); } @@ -1451,7 +1569,7 @@ arc_buf_watch(arc_buf_t *buf) procctl_t ctl; ctl.cmd = PCWATCH; ctl.prwatch.pr_vaddr = (uintptr_t)buf->b_data; - ctl.prwatch.pr_size = buf->b_hdr->b_size; + ctl.prwatch.pr_size = HDR_GET_LSIZE(buf->b_hdr); ctl.prwatch.pr_wflags = WA_WRITE; result = write(arc_procfd, &ctl, sizeof (ctl)); ASSERT3U(result, ==, sizeof (ctl)); @@ -1462,11 +1580,14 @@ arc_buf_watch(arc_buf_t *buf) static arc_buf_contents_t arc_buf_type(arc_buf_hdr_t *hdr) { + arc_buf_contents_t type; if (HDR_ISTYPE_METADATA(hdr)) { - return (ARC_BUFC_METADATA); + type = ARC_BUFC_METADATA; } else { - return (ARC_BUFC_DATA); + type = ARC_BUFC_DATA; } + VERIFY3U(hdr->b_type, ==, type); + return (type); } static uint32_t @@ -1488,29 +1609,29 @@ arc_bufc_to_flags(arc_buf_contents_t typ void arc_buf_thaw(arc_buf_t *buf) { + arc_buf_hdr_t *hdr = buf->b_hdr; + if (zfs_flags & ZFS_DEBUG_MODIFY) { - if (buf->b_hdr->b_l1hdr.b_state != arc_anon) + if (hdr->b_l1hdr.b_state != arc_anon) panic("modifying non-anon buffer!"); - if (HDR_IO_IN_PROGRESS(buf->b_hdr)) + if (HDR_IO_IN_PROGRESS(hdr)) panic("modifying buffer while i/o in progress!"); arc_cksum_verify(buf); } - mutex_enter(&buf->b_hdr->b_l1hdr.b_freeze_lock); - if (buf->b_hdr->b_freeze_cksum != NULL) { - kmem_free(buf->b_hdr->b_freeze_cksum, sizeof (zio_cksum_t)); - buf->b_hdr->b_freeze_cksum = NULL; - } + ASSERT(HDR_HAS_L1HDR(hdr)); + arc_cksum_free(hdr); + mutex_enter(&hdr->b_l1hdr.b_freeze_lock); #ifdef ZFS_DEBUG if (zfs_flags & ZFS_DEBUG_MODIFY) { - if (buf->b_hdr->b_l1hdr.b_thawed != NULL) - kmem_free(buf->b_hdr->b_l1hdr.b_thawed, 1); - buf->b_hdr->b_l1hdr.b_thawed = kmem_alloc(1, KM_SLEEP); + if (hdr->b_l1hdr.b_thawed != NULL) + kmem_free(hdr->b_l1hdr.b_thawed, 1); + hdr->b_l1hdr.b_thawed = kmem_alloc(1, KM_SLEEP); } #endif - mutex_exit(&buf->b_hdr->b_l1hdr.b_freeze_lock); + mutex_exit(&hdr->b_l1hdr.b_freeze_lock); arc_buf_unwatch(buf); } @@ -1518,53 +1639,246 @@ arc_buf_thaw(arc_buf_t *buf) void arc_buf_freeze(arc_buf_t *buf) { + arc_buf_hdr_t *hdr = buf->b_hdr; kmutex_t *hash_lock; if (!(zfs_flags & ZFS_DEBUG_MODIFY)) return; - hash_lock = HDR_LOCK(buf->b_hdr); + hash_lock = HDR_LOCK(hdr); mutex_enter(hash_lock); - ASSERT(buf->b_hdr->b_freeze_cksum != NULL || - buf->b_hdr->b_l1hdr.b_state == arc_anon); - arc_cksum_compute(buf, B_FALSE); + ASSERT(HDR_HAS_L1HDR(hdr)); + ASSERT(hdr->b_l1hdr.b_freeze_cksum != NULL || + hdr->b_l1hdr.b_state == arc_anon); + arc_cksum_compute(buf); mutex_exit(hash_lock); } +/* + * The arc_buf_hdr_t's b_flags should never be modified directly. Instead, + * the following functions should be used to ensure that the flags are + * updated in a thread-safe way. When manipulating the flags either + * the hash_lock must be held or the hdr must be undiscoverable. This + * ensures that we're not racing with any other threads when updating + * the flags. + */ +static inline void +arc_hdr_set_flags(arc_buf_hdr_t *hdr, arc_flags_t flags) +{ + ASSERT(MUTEX_HELD(HDR_LOCK(hdr)) || HDR_EMPTY(hdr)); + hdr->b_flags |= flags; +} + +static inline void +arc_hdr_clear_flags(arc_buf_hdr_t *hdr, arc_flags_t flags) +{ + ASSERT(MUTEX_HELD(HDR_LOCK(hdr)) || HDR_EMPTY(hdr)); + hdr->b_flags &= ~flags; +} + +/* + * Setting the compression bits in the arc_buf_hdr_t's b_flags is + * done in a special way since we have to clear and set bits + * at the same time. Consumers that wish to set the compression bits + * must use this function to ensure that the flags are updated in + * thread-safe manner. + */ +static void +arc_hdr_set_compress(arc_buf_hdr_t *hdr, enum zio_compress cmp) +{ + ASSERT(MUTEX_HELD(HDR_LOCK(hdr)) || HDR_EMPTY(hdr)); + + /* + * Holes and embedded blocks will always have a psize = 0 so + * we ignore the compression of the blkptr and set the + * arc_buf_hdr_t's compression to ZIO_COMPRESS_OFF. + * Holes and embedded blocks remain anonymous so we don't + * want to uncompress them. Mark them as uncompressed. + */ + if (!zfs_compressed_arc_enabled || HDR_GET_PSIZE(hdr) == 0) { + arc_hdr_clear_flags(hdr, ARC_FLAG_COMPRESSED_ARC); + HDR_SET_COMPRESS(hdr, ZIO_COMPRESS_OFF); + ASSERT(!HDR_COMPRESSION_ENABLED(hdr)); + ASSERT3U(HDR_GET_COMPRESS(hdr), ==, ZIO_COMPRESS_OFF); + } else { + arc_hdr_set_flags(hdr, ARC_FLAG_COMPRESSED_ARC); + HDR_SET_COMPRESS(hdr, cmp); + ASSERT3U(HDR_GET_COMPRESS(hdr), ==, cmp); + ASSERT(HDR_COMPRESSION_ENABLED(hdr)); + } +} + +static int +arc_decompress(arc_buf_t *buf) +{ + arc_buf_hdr_t *hdr = buf->b_hdr; + dmu_object_byteswap_t bswap = hdr->b_l1hdr.b_byteswap; + int error; + + if (arc_buf_is_shared(buf)) { + ASSERT3U(HDR_GET_COMPRESS(hdr), ==, ZIO_COMPRESS_OFF); + } else if (HDR_GET_COMPRESS(hdr) == ZIO_COMPRESS_OFF) { + /* + * The arc_buf_hdr_t is either not compressed or is + * associated with an embedded block or a hole in which + * case they remain anonymous. + */ + IMPLY(HDR_COMPRESSION_ENABLED(hdr), HDR_GET_PSIZE(hdr) == 0 || + HDR_GET_PSIZE(hdr) == HDR_GET_LSIZE(hdr)); + ASSERT(!HDR_SHARED_DATA(hdr)); + bcopy(hdr->b_l1hdr.b_pdata, buf->b_data, HDR_GET_LSIZE(hdr)); + } else { + ASSERT(!HDR_SHARED_DATA(hdr)); + ASSERT3U(HDR_GET_LSIZE(hdr), !=, HDR_GET_PSIZE(hdr)); + error = zio_decompress_data(HDR_GET_COMPRESS(hdr), + hdr->b_l1hdr.b_pdata, buf->b_data, HDR_GET_PSIZE(hdr), + HDR_GET_LSIZE(hdr)); + if (error != 0) { + zfs_dbgmsg("hdr %p, compress %d, psize %d, lsize %d", + hdr, HDR_GET_COMPRESS(hdr), HDR_GET_PSIZE(hdr), + HDR_GET_LSIZE(hdr)); + return (SET_ERROR(EIO)); + } + } + if (bswap != DMU_BSWAP_NUMFUNCS) { *** DIFF OUTPUT TRUNCATED AT 1000 LINES ***
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