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alistair23-linux/fs
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Zach Brown 9470dd5d35 fs: check bh blocknr earlier when searching lru 
It's very common for the buffer heads in the lru to have different block
numbers.  By comparing the blocknr before the bdev and size we can
reduce the cost of searching in the very common case where all the
entries have the same bdev and size.

In quick hot cache cycle counting tests on a single fs workstation this
cut the cost of a miss by about 20%.

A diff of the disassembly shows the reordering of the bdev and blocknr
comparisons.  This is in such a tiny loop that skipping one comparison
is a meaningful portion of the total work being done:

     1628:      83 c1 01                add    $0x1,%ecx
     162b:      83 f9 08                cmp    $0x8,%ecx
     162e:      74 60                   je     1690 <__find_get_block+0xa0>
     1630:      89 c8                   mov    %ecx,%eax
     1632:      65 4c 8b 04 c5 00 00    mov    %gs:0x0(,%rax,8),%r8
     1639:      00 00
     163b:      4d 85 c0                test   %r8,%r8
     163e:      4c 89 c3                mov    %r8,%rbx
     1641:      74 e5                   je     1628 <__find_get_block+0x38>
-    1643:      4d 3b 68 30             cmp    0x30(%r8),%r13
+    1643:      4d 3b 68 18             cmp    0x18(%r8),%r13
     1647:      75 df                   jne    1628 <__find_get_block+0x38>
-    1649:      4d 3b 60 18             cmp    0x18(%r8),%r12
+    1649:      4d 3b 60 30             cmp    0x30(%r8),%r12
     164d:      75 d9                   jne    1628 <__find_get_block+0x38>
     164f:      49 39 50 20             cmp    %rdx,0x20(%r8)
     1653:      75 d3                   jne    1628 <__find_get_block+0x38>

Signed-off-by: Zach Brown <zab@zabbo.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-14 02:18:26 +02:00
..
9p 9p: switch to %p[dD] 2014-10-09 02:39:04 -04:00
adfs adfs: add __printf verification, fix format/argument mismatches 2014-08-08 15:57:24 -07:00
affs fs/affs: remove redundant sys_tz declarations 2014-10-14 02:18:22 +02:00
afs Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 16:23:15 +02:00
autofs4 autofs4: d_manage() should return -EISDIR when appropriate in rcu-walk mode. 2014-10-14 02:18:16 +02:00
befs fs/befs/btree.c: remove typedef befs_btree_node 2014-10-14 02:18:20 +02:00
bfs fs/bfs: use bfs prefix for dump_imap 2014-08-08 15:57:24 -07:00
btrfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-10-13 11:28:42 +02:00
cachefiles cachefiles_write_page(): switch to __kernel_write() 2014-10-09 02:39:05 -04:00
ceph vfs: Remove d_drop calls from d_revalidate implementations 2014-10-09 02:38:58 -04:00
cifs cifs: replace strnicmp with strncasecmp 2014-10-14 02:18:24 +02:00
coda fs/coda: use linux/uaccess.h 2014-08-08 15:57:20 -07:00
configfs fs/configfs: use pr_fmt 2014-06-04 16:53:53 -07:00
cramfs fs/cramfs/inode.c: use linux/uaccess.h 2014-08-08 15:57:25 -07:00
debugfs fs: debugfs: remove trailing whitespace 2014-07-09 16:58:21 -07:00
devpts fs/devpts/inode.c: convert printk to pr_foo() 2014-06-06 16:08:14 -07:00
dlm locks: Remove unused conf argument from lm_grant 2014-09-09 16:01:06 -04:00
ecryptfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-10-13 11:28:42 +02:00
efivarfs fs/efivarfs/super.c: use static const for dentry_operations 2014-06-04 16:54:14 -07:00
efs fs/efs/namei.c: return is not a function 2014-08-08 15:57:18 -07:00
exofs fs/exofs/ore_raid.c: replace count*size kzalloc by kcalloc 2014-08-08 15:57:24 -07:00
exportfs fs/exportfs/expfs.c: kernel-doc warning fixes 2014-06-04 16:54:14 -07:00
ext2 percpu_counter: add @gfp to percpu_counter_init() 2014-09-08 09:51:29 +09:00
ext3 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2014-10-11 08:02:31 -04:00
ext4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block into for-3.18 2014-09-24 13:00:21 -04:00
f2fs f2fs: support volatile operations for transient data 2014-10-07 11:54:41 -07:00
fat fat: remove redundant sys_tz declaration 2014-10-14 02:18:20 +02:00
freevxfs
fscache FS-Cache: refcount becomes corrupt under vma pressure. 2014-09-17 22:41:40 +01:00
fuse vfs: Make d_invalidate return void 2014-10-09 02:38:57 -04:00
gfs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-10-13 11:28:42 +02:00
hfs fs/hfs/hfs_fs.h: remove redundant sys_tz declaration 2014-10-14 02:18:20 +02:00
hfsplus Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
hostfs hostfs: support rename flags 2014-08-07 14:40:09 -04:00
hpfs fs/hpfs/dnode.c: fix suspect code indent 2014-08-08 15:57:22 -07:00
hppfs
hugetlbfs fs/hugetlbfs/inode.c: remove null test before kfree 2014-06-04 16:54:11 -07:00
isofs isofs: replace strnicmp with strncasecmp 2014-10-14 02:18:24 +02:00
jbd fs/jbd/revoke.c: replace shift loop by ilog2 2014-05-21 10:26:13 +02:00
jbd2 jbd2: fix descriptor block size handling errors with journal_csum 2014-08-28 22:22:29 -04:00
jffs2 [jffs2] kill wbuf_queued/wbuf_dwork_lock 2014-10-09 02:39:01 -04:00
jfs Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 16:23:15 +02:00
kernfs vfs: Remove unnecessary calls of check_submounts_and_drop 2014-10-09 02:38:56 -04:00
lockd File locking related changes for v3.18 (pile #1) 2014-10-11 13:21:34 -04:00
logfs fs/logfs/readwrite.c: kernel-doc warning fixes 2014-08-06 18:01:12 -07:00
minix minix zmap block counts calculation fix 2014-08-08 15:57:20 -07:00
ncpfs fs/ncpfs/dir.c: remove redundant sys_tz declaration 2014-10-14 02:18:16 +02:00
nfs Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 16:23:15 +02:00
nfs_common lockd: move lockd's grace period handling into its own module 2014-09-17 16:33:11 -04:00
nfsd Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 16:23:15 +02:00
nilfs2 nilfs2: improve the performance of fdatasync() 2014-10-14 02:18:20 +02:00
nls
notify File locking related changes for v3.18 (pile #1) 2014-10-11 13:21:34 -04:00
ntfs ntfs: remove bogus space 2014-10-09 22:25:46 -04:00
ocfs2 ocfs2: replace strnicmp with strncasecmp 2014-10-14 02:18:24 +02:00
omfs FS/OMFS: block number sanity check during fill_super operation 2014-10-14 02:18:22 +02:00
openpromfs
proc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-10-13 11:28:42 +02:00
pstore fs/pstore/ram_core.c: replace count*size kmalloc by kmalloc_array 2014-08-08 15:57:25 -07:00
qnx4
qnx6 fs/qnx6: update debugging to current functions 2014-08-08 15:57:26 -07:00
quota percpu_counter: add @gfp to percpu_counter_init() 2014-09-08 09:51:29 +09:00
ramfs fs/ramfs/file-nommu.c: replace count*size kzalloc by kcalloc 2014-08-08 15:57:18 -07:00
reiserfs fs/reiserfs/journal.c: fix sparse context imbalance warning 2014-10-14 02:18:20 +02:00
romfs fs/romfs/super.c: add blank line after declarations 2014-08-08 15:57:25 -07:00
squashfs fs/squashfs/super.c: logging cleanup 2014-08-06 18:01:13 -07:00
sysfs kernfs: move the last knowledge of sysfs out from kernfs 2014-06-03 08:11:18 -07:00
sysv write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
ubifs UBIFS: Add log overlap assertions 2014-07-31 15:52:51 +03:00
udf udf: Fix loading of special inodes 2014-10-09 13:06:14 +02:00
ufs fs/ufs/balloc.c: remove unused variable 2014-10-14 02:18:20 +02:00
xfs Merge branch 'xfs-misc-fixes-for-3.18-3' into for-next 2014-10-13 10:22:45 +11:00
aio.c percpu_ref: add PERCPU_REF_INIT_* flags 2014-09-24 13:31:50 -04:00
anon_inodes.c
attr.c fs,userns: Change inode_capable to capable_wrt_inode_uidgid 2014-06-10 13:57:22 -07:00
bad_inode.c bad_inode: add ->rename2() 2014-08-07 14:40:09 -04:00
binfmt_aout.c handle suicide on late failure exits in execve() in search_binary_handler() 2014-10-09 02:39:00 -04:00
binfmt_elf.c handle suicide on late failure exits in execve() in search_binary_handler() 2014-10-09 02:39:00 -04:00
binfmt_elf_fdpic.c handle suicide on late failure exits in execve() in search_binary_handler() 2014-10-09 02:39:00 -04:00
binfmt_em86.c
binfmt_flat.c fs/binfmt_flat.c: make old_reloc() static 2014-06-04 16:54:21 -07:00
binfmt_misc.c binfmt_misc: work around gcc-4.9 warning 2014-10-14 02:18:16 +02:00
binfmt_script.c
binfmt_som.c
block_dev.c block_dev: implement readpages() to optimize sequential read 2014-10-09 22:25:53 -04:00
buffer.c fs: check bh blocknr earlier when searching lru 2014-10-14 02:18:26 +02:00
char_dev.c
compat.c vfs: move getname() from callers to do_mount() 2014-10-09 02:39:16 -04:00
compat_binfmt_elf.c
compat_ioctl.c Bluetooth: Move HCI socket definitions into its own header file 2014-07-11 13:53:04 +03:00
coredump.c coredump: add %i/%I in core_pattern to report the tid of the crashed thread 2014-10-14 02:18:21 +02:00
dcache.c take dname_external() into fs/dcache.c 2014-10-12 17:09:05 -04:00
dcookies.c
direct-io.c fuse: honour max_read and max_write in direct_io mode 2014-09-26 21:16:51 -04:00
drop_caches.c fs: convert use of typedef ctl_table to struct ctl_table 2014-06-06 16:08:16 -07:00
eventfd.c
eventpoll.c eventpoll: fix uninitialized variable in epoll_ctl 2014-09-10 15:42:12 -07:00
exec.c handle suicide on late failure exits in execve() in search_binary_handler() 2014-10-09 02:39:00 -04:00
fcntl.c security: make security_file_set_fowner, f_setown and __f_setown void return 2014-09-09 16:01:36 -04:00
fhandle.c
file.c Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 15:44:12 +02:00
file_table.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-10-13 11:28:42 +02:00
filesystems.c
fs-writeback.c sched: Remove proliferation of wait_on_bit() action functions 2014-07-16 15:10:39 +02:00
fs_pin.c make fs/{namespace,super}.c forget about acct.h 2014-08-07 14:40:09 -04:00
fs_struct.c
inode.c mm: allow drivers to prevent new writable mappings 2014-08-08 15:57:31 -07:00
internal.h Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-10-13 11:28:42 +02:00
ioctl.c
Kconfig lockd: move lockd's grace period handling into its own module 2014-09-17 16:33:11 -04:00
Kconfig.binfmt
libfs.c locks: plumb a "priv" pointer into the setlease routines 2014-10-07 14:06:12 -04:00
locks.c locks: flock_make_lock should return a struct file_lock (or PTR_ERR) 2014-10-07 14:06:13 -04:00
Makefile take fs_pin stuff to fs/* 2014-08-07 14:40:08 -04:00
mbcache.c fs/mbcache: replace __builtin_log2() with ilog2() 2014-06-25 22:08:29 -04:00
mount.h vfs: Add a function to lazily unmount all mounts from any dentry. 2014-10-09 02:38:55 -04:00
mpage.c vfs: guard end of device for mpage interface 2014-10-09 22:25:53 -04:00
namei.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-10-13 11:28:42 +02:00
namespace.c vfs: move getname() from callers to do_mount() 2014-10-09 02:39:16 -04:00
no-block.c
open.c vfs: fix check for fallocate on active swapfile 2014-08-01 02:36:04 -04:00
pipe.c new helper: copy_page_from_iter() 2014-05-06 17:39:42 -04:00
pnode.c get rid of propagate_umount() mistakenly treating slaves as busy. 2014-08-30 18:31:41 -04:00
pnode.h
posix_acl.c posix_acl: handle NULL ACL in posix_acl_equiv_mode 2014-05-06 13:58:42 -04:00
proc_namespace.c namespaces: Use task_lock and not rcu to protect nsproxy 2014-07-29 18:08:50 -07:00
read_write.c cachefiles_write_page(): switch to __kernel_write() 2014-10-09 02:39:05 -04:00
readdir.c fanotify: create FAN_ACCESS event for readdir 2014-06-04 16:53:52 -07:00
select.c
seq_file.c fs/seq_file: fallback to vmalloc allocation 2014-07-03 09:21:54 -07:00
signalfd.c
splice.c Merge commit '9f12600fe425bc28f0ccba034a77783c09c15af4' into for-linus 2014-06-12 00:28:09 -04:00
stack.c fs: fix comment for 'CONFIG_LBADF' 2014-08-26 09:35:56 +02:00
stat.c
statfs.c
super.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-10-13 11:28:42 +02:00
sync.c Export sync_filesystem() for modular ->remount_fs() use 2014-09-05 08:16:21 -07:00
timerfd.c timerfd: Remove an always true check 2014-08-27 11:17:48 +02:00
utimes.c
xattr.c vfs: Deduplicate code shared by xattr system calls operating on paths 2014-10-12 17:09:10 -04:00