Date: Thu, 20 Aug 2020 10:06:50 +0000 (UTC) From: Mateusz Guzik <mjg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r364420 - head/sys/kern Message-ID: <202008201006.07KA6o7s042332@repo.freebsd.org>
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Author: mjg Date: Thu Aug 20 10:06:50 2020 New Revision: 364420 URL: https://svnweb.freebsd.org/changeset/base/364420 Log: cache: don't use cache_purge_negative when renaming It avoidably scans (and evicts) unrelated entries. Instead take advantage of passed componentname and perform a hash lookup for the exact one. Sample data from buildworld probed on cache_purge_negative extended to count both scanned and evicted entries on each call are below. At most it has to evict 1. evicted value ------------- Distribution ------------- count -1 | 0 0 |@@@@@@@@@@@@@@@ 19506 1 |@@@@@ 5820 2 |@@@@@@ 7751 4 |@@@@@ 6506 8 |@@@@@ 5996 16 |@@@ 4029 32 |@ 1489 64 | 193 128 | 109 256 | 56 512 | 16 1024 | 7 2048 | 3 4096 | 1 8192 | 1 16384 | 0 scanned value ------------- Distribution ------------- count -1 | 0 0 |@@ 2456 1 |@ 1496 2 |@@ 2728 4 |@@@ 4171 8 |@@@@ 5122 16 |@@@@ 5335 32 |@@@@@ 6279 64 |@@@@ 5671 128 |@@@@ 4558 256 |@@ 3123 512 |@@ 2790 1024 |@@ 2449 2048 |@@ 3021 4096 |@ 1398 8192 |@ 886 16384 | 0 Modified: head/sys/kern/vfs_cache.c Modified: head/sys/kern/vfs_cache.c ============================================================================== --- head/sys/kern/vfs_cache.c Thu Aug 20 10:05:46 2020 (r364419) +++ head/sys/kern/vfs_cache.c Thu Aug 20 10:06:50 2020 (r364420) @@ -2351,9 +2351,13 @@ cache_rename(struct vnode *fdvp, struct vnode *fvp, st ASSERT_VOP_IN_SEQC(tvp); cache_purge(fvp); - if (tvp != NULL) + if (tvp != NULL) { cache_purge(tvp); - cache_purge_negative(tdvp); + KASSERT(!cache_remove_cnp(tdvp, tcnp), + ("%s: lingering negative entry", __func__)); + } else { + cache_remove_cnp(tdvp, tcnp); + } } /*
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