Author: kmacy
Date: Thu May 7 21:51:13 2009
New Revision: 191903
URL: http://svn.freebsd.org/changeset/base/191903
Log:
avoid LOR and gratuitous extra lock acquisitions by moving user_evict list
buffers to
a temporary list
Modified:
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c Thu May 7
20:57:06 2009 (r191902)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c Thu May 7
21:51:13 2009 (r191903)
@@ -1712,14 +1712,23 @@ arc_adjust(void)
static void
arc_do_user_evicts(void)
{
+ static arc_buf_t *tmp_arc_eviction_list;
+
+ /*
+ * Move list over to avoid LOR
+ */
+restart:
mutex_enter(&arc_eviction_mtx);
- while (arc_eviction_list != NULL) {
- arc_buf_t *buf = arc_eviction_list;
- arc_eviction_list = buf->b_next;
+ tmp_arc_eviction_list = arc_eviction_list;
+ arc_eviction_list = NULL;
+ mutex_exit(&arc_eviction_mtx);
+
+ while (tmp_arc_eviction_list != NULL) {
+ arc_buf_t *buf = tmp_arc_eviction_list;
+ tmp_arc_eviction_list = buf->b_next;
rw_enter(&buf->b_lock, RW_WRITER);
buf->b_hdr = NULL;
rw_exit(&buf->b_lock);
- mutex_exit(&arc_eviction_mtx);
if (buf->b_efunc != NULL)
VERIFY(buf->b_efunc(buf) == 0);
@@ -1727,9 +1736,10 @@ arc_do_user_evicts(void)
buf->b_efunc = NULL;
buf->b_private = NULL;
kmem_cache_free(buf_cache, buf);
- mutex_enter(&arc_eviction_mtx);
}
- mutex_exit(&arc_eviction_mtx);
+
+ if (arc_eviction_list != NULL)
+ goto restart;
}
/*
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