Author: mm Date: Tue Jun 28 06:32:35 2011 New Revision: 223622 URL: http://svn.freebsd.org/changeset/base/223622
Log: Disable vdev cache (readahead) by default. The vdev cache is very underutilized (hit ratio 30%-70%) and may consume excessive memory on systems with many vdevs. Illumos-gate revision: 13346 Obtained from: Illumos (Bug #175) MFC after: 1 week Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_cache.c Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_cache.c ============================================================================== --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_cache.c Tue Jun 28 06:26:03 2011 (r223621) +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_cache.c Tue Jun 28 06:32:35 2011 (r223622) @@ -71,9 +71,16 @@ * 1<<zfs_vdev_cache_bshift byte reads by the vdev_cache (aka software * track buffer). At most zfs_vdev_cache_size bytes will be kept in each * vdev's vdev_cache. + * + * TODO: Note that with the current ZFS code, it turns out that the + * vdev cache is not helpful, and in some cases actually harmful. It + * is better if we disable this. Once some time has passed, we should + * actually remove this to simplify the code. For now we just disable + * it by setting the zfs_vdev_cache_size to zero. Note that Solaris 11 + * has made these same changes. */ int zfs_vdev_cache_max = 1<<14; /* 16KB */ -int zfs_vdev_cache_size = 10ULL << 20; /* 10MB */ +int zfs_vdev_cache_size = 0; int zfs_vdev_cache_bshift = 16; #define VCBS (1 << zfs_vdev_cache_bshift) /* 64KB */ _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "[email protected]"
