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Dave Chinner 9bc08a45fb xfs: improve buffer cache hash scalability 
When doing large parallel file creates on a 16p machines, large amounts of
time is being spent in _xfs_buf_find(). A system wide profile with perf top
shows this:

          1134740.00 19.3% _xfs_buf_find
           733142.00 12.5% __ticket_spin_lock

The problem is that the hash contains 45,000 buffers, and the hash table width
is only 256 buffers. That means we've got around 200 buffers per chain, and
searching it is quite expensive. The hash table size needs to increase.

Secondly, every time we do a lookup, we promote the buffer we find to the head
of the hash chain. This is causing cachelines to be dirtied and causes
invalidation of cachelines across all CPUs that may have walked the hash chain
recently. hence every walk of the hash chain is effectively a cold cache walk.
Remove the promotion to avoid this invalidation.

The results are:

          1045043.00 21.2% __ticket_spin_lock
           326184.00  6.6% _xfs_buf_find

A 70% drop in the CPU usage when looking up buffers. Unfortunately that does
not result in an increase in performance underthis workload as contention on
the inode_lock soaks up most of the reduction in CPU usage.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
 		2010-09-02 15:14:38 +10:00
..
linux-2.6 xfs: improve buffer cache hash scalability 2010-09-02 15:14:38 +10:00
quota Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6 2010-08-07 12:57:07 -07:00
support xfs: drop dmapi hooks 2010-07-26 13:16:33 -05:00
Kconfig xfs: use generic Posix ACL code 2009-06-10 17:07:47 +02:00
Makefile xfs: simplify log item descriptor tracking 2010-07-26 13:16:34 -05:00
xfs.h xfs: event tracing support 2009-12-14 23:08:16 -06:00
xfs_acl.h xfs: constify xattr_handler 2010-05-21 18:31:19 -04:00
xfs_ag.h xfs: fix access to upper inodes without inode64 2010-05-28 15:19:56 -05:00
xfs_alloc.c xfs: fix gcc 4.6 set but not read and unused statement warnings 2010-07-26 13:16:51 -05:00
xfs_alloc.h xfs: do not use emums for flags used in tracing 2010-07-26 13:16:43 -05:00
xfs_alloc_btree.c xfs: remove unneeded #include statements 2010-07-26 13:16:33 -05:00
xfs_alloc_btree.h [XFS] Always use struct xfs_btree_block instead of short / longform 2008-10-30 17:14:34 +11:00
xfs_arch.h xfs: use generic Posix ACL code 2009-06-10 17:07:47 +02:00
xfs_attr.c xfs: remove unused delta tracking code in xfs_bmapi 2010-07-26 13:16:39 -05:00
xfs_attr.h xfs: convert attr to use unsigned names 2010-01-20 10:47:48 +11:00
xfs_attr_leaf.c xfs: remove unused delta tracking code in xfs_bmapi 2010-07-26 13:16:39 -05:00
xfs_attr_leaf.h [XFS] Remove macro-to-function indirections in attr code 2009-01-09 15:46:44 +11:00
xfs_attr_sf.h xfs: convert attr to use unsigned names 2010-01-20 10:47:48 +11:00
xfs_bit.c [XFS] Use the generic bitops rather than implementing them ourselves. 2008-08-13 15:41:12 +10:00
xfs_bit.h [XFS] Remove macro-to-function indirections in the mask code 2009-01-09 15:53:54 +11:00
xfs_bmap.c xfs: clean up xfs_bmap_get_bp 2010-07-26 13:16:53 -05:00
xfs_bmap.h xfs: remove unused delta tracking code in xfs_bmapi 2010-07-26 13:16:39 -05:00
xfs_bmap_btree.c xfs: remove unneeded #include statements 2010-07-26 13:16:33 -05:00
xfs_bmap_btree.h xfs: make several more functions static 2010-01-15 15:31:38 -06:00
xfs_btree.c xfs: remove unneeded #include statements 2010-07-26 13:16:33 -05:00
xfs_btree.h xfs: add more statics & drop some unused functions 2009-08-31 14:46:20 -05:00
xfs_btree_trace.c [XFS] make btree tracing generic 2008-10-30 16:58:50 +11:00
xfs_btree_trace.h xfs: event tracing support 2009-12-14 23:08:16 -06:00
xfs_buf_item.c xfs: kill the b_strat callback in xfs_buf 2010-07-26 13:16:52 -05:00
xfs_buf_item.h xfs: give li_cb callbacks the correct prototype 2010-07-26 13:16:35 -05:00
xfs_da_btree.c xfs: fix gcc 4.6 set but not read and unused statement warnings 2010-07-26 13:16:51 -05:00
xfs_da_btree.h xfs: convert dirnameops to unsigned char names 2010-01-20 10:47:17 +11:00
xfs_dfrag.c xfs: simplify inode to transaction joining 2010-07-26 13:16:36 -05:00
xfs_dfrag.h xfs: clean up inconsistent variable naming in xfs_swap_extent 2010-01-15 15:31:23 -06:00
xfs_dinode.h xfs: remove m_litino 2009-03-29 09:51:14 +02:00
xfs_dir2.c xfs: split xfs_itrace_entry 2010-07-26 13:16:44 -05:00
xfs_dir2.h xfs: make xfs_dir_cilookup_result use unsigned char 2010-01-20 10:47:25 +11:00
xfs_dir2_block.c xfs: fix gcc 4.6 set but not read and unused statement warnings 2010-07-26 13:16:51 -05:00
xfs_dir2_block.h
…
xfs_dir2_data.c xfs: remove unneeded #include statements 2010-07-26 13:16:33 -05:00
xfs_dir2_data.h xfs: fix various typos 2009-03-29 09:55:42 +02:00
xfs_dir2_leaf.c xfs: remove unused delta tracking code in xfs_bmapi 2010-07-26 13:16:39 -05:00
xfs_dir2_leaf.h
…
xfs_dir2_node.c xfs: remove unneeded #include statements 2010-07-26 13:16:33 -05:00
xfs_dir2_node.h xfs: make several more functions static 2010-01-15 15:31:38 -06:00
xfs_dir2_sf.c xfs: remove unneeded #include statements 2010-07-26 13:16:33 -05:00
xfs_dir2_sf.h [XFS] kill xfs_dinode_core_t 2008-12-01 11:37:35 +11:00
xfs_error.c xfs: remove unneeded #include statements 2010-07-26 13:16:33 -05:00
xfs_error.h xfs: add const qualifiers to xfs error function args 2010-05-19 09:58:11 -05:00
xfs_extfree_item.c xfs: fix the xfs_log_iovec i_addr type 2010-07-26 13:16:36 -05:00
xfs_extfree_item.h [XFS] remove always-true #ifndef HAVE_FORMAT32 tests 2009-01-22 14:07:31 +11:00
xfs_filestream.c xfs: clean up filestreams helpers 2010-07-26 13:16:51 -05:00
xfs_filestream.h xfs: clean up filestreams helpers 2010-07-26 13:16:51 -05:00
xfs_fs.h xfs: return inode fork offset in bulkstat for fsr 2010-03-05 11:02:07 -06:00
xfs_fsops.c xfs: dummy transactions should not dirty VFS state 2010-08-24 11:46:31 +10:00
xfs_fsops.h xfs: dummy transactions should not dirty VFS state 2010-08-24 11:46:31 +10:00
xfs_ialloc.c xfs: fix untrusted inode number lookup 2010-08-24 11:42:30 +10:00
xfs_ialloc.h xfs: rationalize xfs_inobt_lookup* 2009-09-01 12:45:39 -05:00
xfs_ialloc_btree.c xfs: remove unneeded #include statements 2010-07-26 13:16:33 -05:00
xfs_ialloc_btree.h xfs: remove superflous inobt macros 2009-02-09 08:37:14 +01:00
xfs_iget.c xfs: fix gcc 4.6 set but not read and unused statement warnings 2010-07-26 13:16:51 -05:00
xfs_inode.c xfs: ensure we mark all inodes in a freed cluster XFS_ISTALE 2010-08-24 11:42:41 +10:00
xfs_inode.h xfs: simplify and remove xfs_ireclaim 2010-07-26 13:16:48 -05:00
xfs_inode_item.c xfs: fix big endian build 2010-07-26 16:07:38 -05:00
xfs_inode_item.h xfs: simplify inode to transaction joining 2010-07-26 13:16:36 -05:00
xfs_inum.h xfs: remove XFS_INO64_OFFSET 2009-08-31 14:46:22 -05:00
xfs_iomap.c xfs: small cleanups for xfs_iomap / __xfs_get_blocks 2010-07-26 13:16:42 -05:00
xfs_iomap.h xfs: do not use emums for flags used in tracing 2010-07-26 13:16:43 -05:00
xfs_itable.c xfs: remove xfs_iput 2010-07-26 13:16:44 -05:00
xfs_itable.h xfs: remove block number from inode lookup code 2010-06-24 11:35:17 +10:00
xfs_log.c xfs: Reduce log force overhead for delayed logging 2010-08-24 11:40:03 +10:00
xfs_log.h xfs: remove the unused XFS_LOG_SLEEP and XFS_LOG_NOSLEEP flags 2010-07-26 13:16:38 -05:00
xfs_log_cil.c xfs: don't do memory allocation under the CIL context lock 2010-08-24 11:45:53 +10:00
xfs_log_priv.h xfs: Reduce log force overhead for delayed logging 2010-08-24 11:40:03 +10:00
xfs_log_recover.c xfs: fix the xfs_log_iovec i_addr type 2010-07-26 13:16:36 -05:00
xfs_log_recover.h xfs: Clean up XFS_BLI_* flag namespace 2010-05-24 10:33:39 -05:00
xfs_mount.c xfs: remove unneeded #include statements 2010-07-26 13:16:33 -05:00
xfs_mount.h xfs: remove obsolete osyncisosync mount option 2010-07-26 13:16:51 -05:00
xfs_mru_cache.c xfs: Kill filestreams cache flush 2010-01-15 15:34:22 -06:00
xfs_mru_cache.h xfs: Kill filestreams cache flush 2010-01-15 15:34:22 -06:00
xfs_quota.h xfs: removed unused XFS_QMOPT_ flags 2010-05-19 09:58:15 -05:00
xfs_refcache.h
…
xfs_rename.c xfs: split xfs_itrace_entry 2010-07-26 13:16:44 -05:00
xfs_rtalloc.c xfs: remove unused delta tracking code in xfs_bmapi 2010-07-26 13:16:39 -05:00
xfs_rtalloc.h xfs: be more explicit if RT mount fails due to config 2010-05-28 14:58:24 -05:00
xfs_rw.c xfs: remove unneeded #include statements 2010-07-26 13:16:33 -05:00
xfs_rw.h xfs: only clear the suid bit once in xfs_write 2010-02-12 13:43:57 -06:00
xfs_sb.h [XFS] Remove the rest of the macro-to-function indirections. 2009-01-19 14:45:55 +11:00
xfs_trans.c xfs: unlock items before allowing the CIL to commit 2010-08-24 11:42:52 +10:00
xfs_trans.h xfs: remove the unused XFS_TRANS_NOSLEEP/XFS_TRANS_WAIT flags 2010-07-26 13:16:38 -05:00
xfs_trans_ail.c xfs: drop dmapi hooks 2010-07-26 13:16:33 -05:00
xfs_trans_buf.c xfs: give li_cb callbacks the correct prototype 2010-07-26 13:16:35 -05:00
xfs_trans_extfree.c xfs: simplify log item descriptor tracking 2010-07-26 13:16:34 -05:00
xfs_trans_inode.c xfs: simplify inode to transaction joining 2010-07-26 13:16:36 -05:00
xfs_trans_priv.h xfs: unlock items before allowing the CIL to commit 2010-08-24 11:42:52 +10:00
xfs_trans_space.h xfs: remove superflous inobt macros 2009-02-09 08:37:14 +01:00
xfs_types.h xfs: make the log ticket ID available outside the log infrastructure 2010-05-24 10:33:52 -05:00
xfs_utils.c xfs: simplify xfs_truncate_file 2010-07-26 13:16:52 -05:00
xfs_utils.h xfs: simplify xfs_truncate_file 2010-07-26 13:16:52 -05:00
xfs_vnodeops.c xfs: new truncate sequence 2010-08-09 16:47:42 -04:00
xfs_vnodeops.h xfs: kill xfs_lrw.h 2010-03-01 16:35:44 -06:00