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Eric Dumazet 163da958ba [PATCH] FS: speed up rw_verify_area() 
oprofile hunting showed a stall in rw_verify_area(), because of triple
indirection and potential cache misses.
(file->f_path.dentry->d_inode->i_flock)

By moving initialization of 'struct inode' pointer before the pos/count
sanity tests, we allow the compiler and processor to perform two loads by
anticipation, reducing stall, without prefetch() hints.  Even x86 arch has
enough registers to not use temporary variables and not increase text size.

I validated this patch running a bench and studied oprofile changes, and
absolute perf of the test program.

Results of my epoll_pipe_bench (source available on request) on a Pentium-M
1.6 GHz machine

Before :
# ./epoll_pipe_bench -l 30 -t 20
Avg: 436089 evts/sec read_count=8843037 write_count=8843040 21.218390 samples
per call
(best value out of 10 runs)

After :
# ./epoll_pipe_bench -l 30 -t 20
Avg: 470980 evts/sec read_count=9549871 write_count=9549894 21.216694 samples
per call
(best value out of 10 runs)

oprofile CPU_CLK_UNHALTED events gave a reduction from 5.3401 % to 2.5851 %
for the rw_verify_area() function.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2007-02-12 09:48:29 -08:00
..
9p [PATCH] remove invalidate_inode_pages() 2007-02-11 10:51:31 -08:00
adfs [PATCH] adfs: fix filename handling 2007-01-05 23:55:22 -08:00
affs [PATCH] affs: change uses of f_{dentry, vfsmnt} to use f_path 2006-12-08 08:28:43 -08:00
afs [PATCH] rename struct namespace to struct mnt_namespace 2006-12-08 08:28:51 -08:00
autofs [PATCH] autofs: change uses of f_{dentry, vfsmnt} to use f_path 2006-12-08 08:28:43 -08:00
autofs4 [PATCH] getting rid of all casts of k[cmz]alloc() calls 2006-12-13 09:05:58 -08:00
befs [PATCH] getting rid of all casts of k[cmz]alloc() calls 2006-12-13 09:05:58 -08:00
bfs [PATCH] update Tigran's email addresses 2006-12-13 09:05:53 -08:00
cifs [CIFS] Minor cleanup 2007-02-06 20:43:30 +00:00
coda [PATCH] seq_file conversion: coda 2007-02-11 10:51:34 -08:00
configfs [PATCH] Transform kmem_cache_alloc()+memset(0) -> kmem_cache_zalloc(). 2007-02-11 10:51:27 -08:00
cramfs [PATCH] struct path: convert cramfs 2006-12-08 08:28:44 -08:00
debugfs DebugFS : file/directory removal fix 2006-12-13 15:38:45 -08:00
devpts [PATCH] inode-diet: Eliminate i_blksize from the inode structure 2006-09-27 08:26:18 -07:00
dlm [PATCH] Transform kmem_cache_alloc()+memset(0) -> kmem_cache_zalloc(). 2007-02-11 10:51:27 -08:00
ecryptfs [PATCH] Transform kmem_cache_alloc()+memset(0) -> kmem_cache_zalloc(). 2007-02-11 10:51:27 -08:00
efs [PATCH] struct path: convert efs 2006-12-08 08:28:45 -08:00
exportfs [PATCH] VFS: Make filldir_t and struct kstat deal in 64-bit inode numbers 2006-10-03 08:03:40 -07:00
ext2 [PATCH] fix umask when noACL kernel meets extN tuned for ACLs 2007-02-11 10:51:34 -08:00
ext3 [PATCH] jbd layer function called instead of fs specific one 2007-02-11 11:18:06 -08:00
ext4 [PATCH] jbd layer function called instead of fs specific one 2007-02-11 11:18:06 -08:00
fat [PATCH] fat: change uses of f_{dentry,vfsmnt} to use f_path 2006-12-08 08:28:41 -08:00
freevxfs [PATCH] struct path: convert freevxfs 2006-12-08 08:28:45 -08:00
fuse [PATCH] remove invalidate_inode_pages() 2007-02-11 10:51:31 -08:00
gfs2 [PATCH] Transform kmem_cache_alloc()+memset(0) -> kmem_cache_zalloc(). 2007-02-11 10:51:27 -08:00
hfs [PATCH] extend the set of "__attribute__" shortcut macros 2007-02-11 10:51:35 -08:00
hfsplus [PATCH] extend the set of "__attribute__" shortcut macros 2007-02-11 10:51:35 -08:00
hostfs [PATCH] uml: fix mknod 2007-01-30 08:26:44 -08:00
hpfs [PATCH] struct path: convert hpfs 2006-12-08 08:28:45 -08:00
hppfs [PATCH] struct path: convert hppfs 2006-12-08 08:28:45 -08:00
hugetlbfs [PATCH] hugetlb: preserve hugetlb pte dirty state 2007-02-09 09:25:46 -08:00
isofs [PATCH] isofs: change uses of f_{dentry, vfsmnt} to use f_path 2006-12-08 08:28:41 -08:00
jbd [PATCH] jbd: wait for already submitted t_sync_datalist buffer to complete 2006-12-22 08:55:51 -08:00
jbd2 [PATCH] jbd2: wait for already submitted t_sync_datalist buffer to complete 2006-12-07 08:39:42 -08:00
jffs [PATCH] remove invalidate_inode_pages() 2007-02-11 10:51:31 -08:00
jffs2 Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 2007-01-18 10:34:51 +11:00
jfs JFS: Remove incorrect kgdb define 2007-01-26 10:14:36 -06:00
lockd [PATCH] fs/lockd/clntlock.c: add missing newlines to dprintk's 2007-01-30 08:26:45 -08:00
minix [PATCH] struct path: convert minix 2006-12-08 08:28:47 -08:00
msdos [PATCH] fat: add fat_getattr() 2006-11-16 11:43:38 -08:00
ncpfs [PATCH] ncpfs: ensure we free wdog_pid on parse_option or fill_inode failure 2006-12-13 09:05:53 -08:00
nfs [PATCH] Remove warning: VFS is out of sync with lock manager 2007-01-30 16:01:35 -08:00
nfs_common [PATCH] nfs_common endianness annotations 2006-10-20 10:26:41 -07:00
nfsd [PATCH] endianness bug: ntohl() misspelled as >> 24 in fh_verify(). 2007-02-01 16:17:06 -08:00
nls [PATCH] fs: make nls_cp936.c handle some U00XY characters and U20AC correctly 2006-12-07 08:39:46 -08:00
ntfs [PATCH] NTFS: rename incorrect check of NTFS_DEBUG with just DEBUG 2007-02-12 09:48:27 -08:00
ocfs2 [PATCH] ocfs2 heartbeat: clean up bio submission code 2007-02-07 12:15:58 -08:00
openpromfs [PATCH] struct path: convert openpromfs 2006-12-08 08:28:48 -08:00
partitions Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6 2007-02-11 11:37:45 -08:00
proc [PATCH] ifdef ->rchar, ->wchar, ->syscr, ->syscw from task_struct 2007-02-11 11:18:07 -08:00
qnx4 [PATCH] struct path: convert qnx4 2006-12-08 08:28:48 -08:00
ramfs [PATCH] convert ramfs to use __set_page_dirty_no_writeback 2007-02-11 10:51:19 -08:00
reiserfs [PATCH] reiserfs: Use ARRAY_SIZE macro when appropriate 2007-02-12 09:48:29 -08:00
romfs [PATCH] struct path: convert romfs 2006-12-08 08:28:49 -08:00
smbfs [PATCH] Transform kmem_cache_alloc()+memset(0) -> kmem_cache_zalloc(). 2007-02-11 10:51:27 -08:00
sysfs [PATCH] Transform kmem_cache_alloc()+memset(0) -> kmem_cache_zalloc(). 2007-02-11 10:51:27 -08:00
sysv [PATCH] fs/sysv/: proper prototypes for 2 functions 2006-12-22 08:55:47 -08:00
udf [PATCH] struct path: convert udf 2006-12-08 08:28:50 -08:00
ufs [PATCH] ufs: restore back support of openstep 2007-02-09 09:25:46 -08:00
vfat [PATCH] fat: add fat_getattr() 2006-11-16 11:43:38 -08:00
xfs [PATCH] Make XFS use BH_Unwritten and BH_Delay correctly 2007-02-12 09:48:27 -08:00
Kconfig [PATCH] Remove unused kernel config option ZISOFS_FS 2007-02-11 11:18:06 -08:00
Kconfig.binfmt [PATCH] frv: suppress configuration of certain features for FRV 2006-01-08 20:13:36 -08:00
Makefile [PATCH] fsstack: Introduce fsstack_copy_{attr,inode}_* 2006-12-08 08:28:40 -08:00
aio.c [PATCH] Transform kmem_cache_alloc()+memset(0) -> kmem_cache_zalloc(). 2007-02-11 10:51:27 -08:00
attr.c [PATCH] capable/capability.h (fs/) 2006-01-11 18:42:13 -08:00
bad_inode.c [PATCH] fix memory corruption from misinterpreted bad_inode_ops return values 2007-01-05 23:55:23 -08:00
binfmt_aout.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
binfmt_elf.c [PATCH] core-dumping unreadable binaries via PT_INTERP 2007-01-26 13:51:00 -08:00
binfmt_elf_fdpic.c [PATCH] Remove final references to deprecated "MAP_ANON" page protection flag 2007-02-11 10:51:17 -08:00
binfmt_em86.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
binfmt_flat.c [PATCH] uclinux: correctly remap bin_fmtflat exe allocated mem regions 2007-02-09 10:45:33 -08:00
binfmt_misc.c [PATCH] getting rid of all casts of k[cmz]alloc() calls 2006-12-13 09:05:58 -08:00
binfmt_script.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
binfmt_som.c [PARISC] Fix fs/binfmt_som.c 2006-10-04 06:51:26 -06:00
bio.c [PATCH] optimize o_direct on block devices 2006-12-13 09:05:50 -08:00
block_dev.c [PATCH] revert blockdev direct io back to 2.6.19 version 2007-02-03 11:26:06 -08:00
buffer.c [PATCH] warning fix: unsigned->signed 2007-02-12 09:48:29 -08:00
char_dev.c [PATCH] register_chrdev_region() don't hand out the LOCAL/EXPERIMENTAL majors 2007-02-12 09:48:27 -08:00
compat.c [PATCH] fdtable: Make fdarray and fdsets equal in size 2006-12-10 09:57:22 -08:00
compat_ioctl.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
dcache.c [PATCH] Fix d_path for lazy unmounts 2007-02-12 09:48:27 -08:00
dcookies.c [PATCH] slab: remove kmem_cache_t 2006-12-07 08:39:25 -08:00
direct-io.c [PATCH] dio: lock refcount operations 2006-12-10 09:57:21 -08:00
dnotify.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
dquot.c [PATCH] remove sb->s_files and file_list_lock usage in dquot.c 2007-02-12 09:48:28 -08:00
drop_caches.c [PATCH] remove invalidate_inode_pages() 2007-02-11 10:51:31 -08:00
eventpoll.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
exec.c [PATCH] Transform kmem_cache_alloc()+memset(0) -> kmem_cache_zalloc(). 2007-02-11 10:51:27 -08:00
fcntl.c [PATCH] fdtable: Make fdarray and fdsets equal in size 2006-12-10 09:57:22 -08:00
fifo.c [PATCH] pipe.c/fifo.c code cleanups 2006-04-11 13:53:33 +02:00
file.c [PATCH] fdtable: Provide free_fdtable() wrapper 2006-12-22 08:55:50 -08:00
file_table.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
filesystems.c [PATCH] Ban register_filesystem(NULL); 2006-09-29 09:18:20 -07:00
fs-writeback.c Write back inode data pages even when the inode itself is locked 2007-01-26 12:53:20 -08:00
generic_acl.c [PATCH] Generic infrastructure for acls 2006-09-29 09:18:24 -07:00
inode.c [PATCH] move remove_dquot_ref to dqout.c 2007-02-12 09:48:28 -08:00
inotify.c [PATCH] severing fs.h, radix-tree.h -> sched.h 2006-12-04 02:00:24 -05:00
inotify_user.c [PATCH] inotify: read return val fix 2007-02-12 09:48:28 -08:00
internal.h [PATCH] CONFIG_BLOCK internal.h cleanups 2006-09-30 20:52:32 +02:00
ioctl.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
ioprio.c [PATCH] block layer: ioprio_best function fix 2006-10-12 15:09:51 +02:00
libfs.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
locks.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
mbcache.c [PATCH] slab: remove kmem_cache_t 2006-12-07 08:39:25 -08:00
mpage.c [PATCH] BLOCK: Dissociate generic_writepages() from mpage stuff [try #6] 2006-09-30 20:52:26 +02:00
namei.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
namespace.c [PATCH] Transform kmem_cache_alloc()+memset(0) -> kmem_cache_zalloc(). 2007-02-11 10:51:27 -08:00
nfsctl.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
no-block.c [PATCH] BLOCK: Make it possible to disable the block layer [try #6] 2006-09-30 20:52:31 +02:00
open.c [PATCH] fdtable: Make fdarray and fdsets equal in size 2006-12-10 09:57:22 -08:00
pipe.c [PATCH] fix leaks on pipe(2) failure exits 2006-12-21 00:16:03 -08:00
pnode.c [PATCH] rename struct namespace to struct mnt_namespace 2006-12-08 08:28:51 -08:00
pnode.h [PATCH] rename struct namespace to struct mnt_namespace 2006-12-08 08:28:51 -08:00
posix_acl.c [PATCH] kmemdup: some users 2006-10-01 00:39:19 -07:00
quota.c [PATCH] BLOCK: Make it possible to disable the block layer [try #6] 2006-09-30 20:52:31 +02:00
quota_v1.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
quota_v2.c [PATCH] sem2mutex: quota 2006-03-23 07:38:11 -08:00
read_write.c [PATCH] FS: speed up rw_verify_area() 2007-02-12 09:48:29 -08:00
read_write.h [PATCH] Remove readv/writev methods and use aio_read/aio_write instead 2006-10-01 00:39:28 -07:00
readdir.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
select.c [PATCH] fdtable: Make fdarray and fdsets equal in size 2006-12-10 09:57:22 -08:00
seq_file.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
splice.c [PATCH] constify pipe_buf_operations 2006-12-13 09:05:47 -08:00
stack.c [PATCH] fsstack: Remove inode copy 2006-12-22 08:55:48 -08:00
stat.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
super.c [PATCH] Revert bd_mount_mutex back to a semaphore 2007-01-11 18:18:21 -08:00
sync.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
utimes.c [PATCH] severing fs.h, radix-tree.h -> sched.h 2006-12-04 02:00:24 -05:00
xattr.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
xattr_acl.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00