Date: Sun, 17 Jul 2022 11:24:15 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 5d32157d4e5c - main - vm_object: Modify vm_object_allocate_anon() to return OBJT_SWAP objects Message-ID: <202207171124.26HBOFmv014176@gitrepo.freebsd.org>
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The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=5d32157d4e5c2dfda5ca39d40bf4620b04fc2b29 commit 5d32157d4e5c2dfda5ca39d40bf4620b04fc2b29 Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2022-07-16 15:27:27 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2022-07-17 11:09:48 +0000 vm_object: Modify vm_object_allocate_anon() to return OBJT_SWAP objects With this change, OBJT_DEFAULT objects are no longer allocated. Instead, anonymous objects are always of type OBJT_SWAP and always have OBJ_SWAP set. Modify the page fault handler to check the swap block radix tree in places where it checked for objects of type OBJT_DEFAULT. In particular, there's no need to invoke getpages for an OBJT_SWAP object with no swap blocks assigned. Reviewed by: alc, kib Tested by: pho Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D35785 --- sys/vm/vm_fault.c | 25 ++++++++++++++++++++----- sys/vm/vm_object.c | 8 +++++--- sys/vm/vm_object.h | 3 ++- 3 files changed, 27 insertions(+), 9 deletions(-) diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c index c379301f866f..d398be941e84 100644 --- a/sys/vm/vm_fault.c +++ b/sys/vm/vm_fault.c @@ -85,6 +85,7 @@ __FBSDID("$FreeBSD$"); #include <sys/lock.h> #include <sys/mman.h> #include <sys/mutex.h> +#include <sys/pctrie.h> #include <sys/proc.h> #include <sys/racct.h> #include <sys/refcount.h> @@ -220,6 +221,21 @@ fault_page_free(vm_page_t *mp) } } +/* + * Return true if a vm_pager_get_pages() call is needed in order to check + * whether the pager might have a particular page, false if it can be determined + * immediately that the pager can not have a copy. For swap objects, this can + * be checked quickly. + */ +static inline bool +fault_object_needs_getpages(vm_object_t object) +{ + VM_OBJECT_ASSERT_LOCKED(object); + + return ((object->flags & OBJ_SWAP) == 0 || + !pctrie_is_empty(&object->un_pager.swp.swp_blks)); +} + static inline void unlock_map(struct faultstate *fs) { @@ -1406,10 +1422,9 @@ vm_fault_object(struct faultstate *fs, int *behindp, int *aheadp) /* * Page is not resident. If the pager might contain the page * or this is the beginning of the search, allocate a new - * page. (Default objects are zero-fill, so there is no real - * pager for them.) + * page. */ - if (fs->m == NULL && (fs->object->type != OBJT_DEFAULT || + if (fs->m == NULL && (fault_object_needs_getpages(fs->object) || fs->object == fs->first_object)) { res = vm_fault_allocate(fs); if (res != FAULT_CONTINUE) @@ -1422,7 +1437,7 @@ vm_fault_object(struct faultstate *fs, int *behindp, int *aheadp) * object without dropping the lock to preserve atomicity of * shadow faults. */ - if (fs->object->type != OBJT_DEFAULT) { + if (fault_object_needs_getpages(fs->object)) { /* * At this point, we have either allocated a new page * or found an existing page that is only partially @@ -1841,7 +1856,7 @@ vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra, if (!obj_locked) VM_OBJECT_RLOCK(lobject); while ((m = vm_page_lookup(lobject, pindex)) == NULL && - lobject->type == OBJT_DEFAULT && + !fault_object_needs_getpages(lobject) && (backing_object = lobject->backing_object) != NULL) { KASSERT((lobject->backing_object_offset & PAGE_MASK) == 0, ("vm_fault_prefault: unaligned object offset")); diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c index 4272a734b233..57904454eff7 100644 --- a/sys/vm/vm_object.c +++ b/sys/vm/vm_object.c @@ -244,8 +244,10 @@ _vm_object_allocate(objtype_t type, vm_pindex_t size, u_short flags, object->type = type; object->flags = flags; - if ((flags & OBJ_SWAP) != 0) + if ((flags & OBJ_SWAP) != 0) { pctrie_init(&object->un_pager.swp.swp_blks); + object->un_pager.swp.writemappings = 0; + } /* * Ensure that swap_pager_swapoff() iteration over object_list @@ -473,8 +475,8 @@ vm_object_allocate_anon(vm_pindex_t size, vm_object_t backing_object, else handle = backing_object; object = uma_zalloc(obj_zone, M_WAITOK); - _vm_object_allocate(OBJT_DEFAULT, size, OBJ_ANON | OBJ_ONEMAPPING, - object, handle); + _vm_object_allocate(OBJT_SWAP, size, + OBJ_ANON | OBJ_ONEMAPPING | OBJ_SWAP, object, handle); object->cred = cred; object->charge = cred != NULL ? charge : 0; return (object); diff --git a/sys/vm/vm_object.h b/sys/vm/vm_object.h index 80e84dcabf98..719198637726 100644 --- a/sys/vm/vm_object.h +++ b/sys/vm/vm_object.h @@ -202,7 +202,8 @@ struct vm_object { #define OBJ_SIZEVNLOCK 0x0040 /* lock vnode to check obj size */ #define OBJ_PG_DTOR 0x0080 /* dont reset object, leave that for dtor */ #define OBJ_SHADOWLIST 0x0100 /* Object is on the shadow list. */ -#define OBJ_SWAP 0x0200 /* object swaps */ +#define OBJ_SWAP 0x0200 /* object swaps, type will be OBJT_SWAP + or dynamically registered */ #define OBJ_SPLIT 0x0400 /* object is being split */ #define OBJ_COLLAPSING 0x0800 /* Parent of collapse. */ #define OBJ_COLORED 0x1000 /* pg_color is defined */
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