Date: Fri, 17 Feb 2017 17:52:12 +0000 (UTC) From: Josh Paetzel <jpaetzel@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r313879 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs Message-ID: <201702171752.v1HHqCXQ032486@repo.freebsd.org>
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Author: jpaetzel Date: Fri Feb 17 17:52:12 2017 New Revision: 313879 URL: https://svnweb.freebsd.org/changeset/base/313879 Log: MVF: 313876 7504 kmem_reap hangs spa_sync and administrative tasks illumos/illumos-gate@405a5a0f5c3ab36cb76559467d1a62ba648bd809 https://github.com/illumos/illumos-gate/commit/405a5a0f5c3ab36cb76559467d1a62ba648bd80 https://www.illumos.org/issues/7504 We see long spa_sync(). We are waiting to hold dp_config_rwlock for writer. Some other thread holds dp_config_rwlock for reader, then calls arc_get_data_buf(), which finds that arc_is_overflowing()==B_TRUE. So it waits (while holding dp_config_rwlock for reader) for arc_reclaim_thread to signal arc_reclaim_waiters_cv. Before signaling, arc_reclaim_thread does arc_kmem_reap_now(), which takes ~seconds. Author: Matthew Ahrens <mahrens@delphix.com> Reviewed by: George Wilson <george.wilson@delphix.com> Reviewed by: Prakash Surya <prakash.surya@delphix.com> Approved by: Dan McDonald <danmcd@omniti.com> Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c Directory Properties: head/sys/cddl/contrib/opensolaris/ (props changed) Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c ============================================================================== --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c Fri Feb 17 15:40:24 2017 (r313878) +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c Fri Feb 17 17:52:12 2017 (r313879) @@ -4086,7 +4086,6 @@ arc_reclaim_thread(void *dummy __unused) mutex_enter(&arc_reclaim_lock); while (!arc_reclaim_thread_exit) { - int64_t free_memory = arc_available_memory(); uint64_t evicted = 0; /* @@ -4105,6 +4104,14 @@ arc_reclaim_thread(void *dummy __unused) mutex_exit(&arc_reclaim_lock); + /* + * We call arc_adjust() before (possibly) calling + * arc_kmem_reap_now(), so that we can wake up + * arc_get_data_buf() sooner. + */ + evicted = arc_adjust(); + + int64_t free_memory = arc_available_memory(); if (free_memory < 0) { arc_no_grow = B_TRUE; @@ -4138,8 +4145,6 @@ arc_reclaim_thread(void *dummy __unused) arc_no_grow = B_FALSE; } - evicted = arc_adjust(); - mutex_enter(&arc_reclaim_lock); /*
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