LU-5240 obdclass: Increase minimum LU Cache for ZFS

If the lu cache is too small threads will thrash for data including
the OI tables and other important metadata.

This patch is back-ported from the following one:
Lustre-commit: a9c51c03eaecb5234ba754b738877323a35bed51
Lustre-change: http://review.whamcloud.com/10802

Test-Parameters: alwaysuploadlogs \
mdtfilesystemtype=zfs mdsfilesystemtype=zfs ostfilesystemtype=zfs \
testgroup=review-zfs

Signed-off-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Change-Id: Ia6c85f523219706b5d41054c869e73ed5bf3c2f5
Reviewed-on: http://review.whamcloud.com/12002
Tested-by: Jenkins
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Tested-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lustre/obdclass/lu_object.c b/lustre/obdclass/lu_object.c
index 320374c..0b8df84 100644 (file)
--- a/lustre/obdclass/lu_object.c
+++ b/lustre/obdclass/lu_object.c
@@ -69,7 +69,8 @@ enum {
 #define        LU_CACHE_NR_UNLIMITED           -1
 #define        LU_CACHE_NR_DEFAULT             LU_CACHE_NR_UNLIMITED
 #define        LU_CACHE_NR_LDISKFS_LIMIT       LU_CACHE_NR_UNLIMITED
-#define        LU_CACHE_NR_ZFS_LIMIT           256
+/** This is set to roughly (20 * OSS_NTHRS_MAX) to prevent thrashing */
+#define        LU_CACHE_NR_ZFS_LIMIT           10240
 
 #define LU_SITE_BITS_MIN    12
 #define LU_SITE_BITS_MAX    24