diff options
| author | npiggin@suse.de <npiggin@suse.de> | 2009-04-26 20:25:55 +1000 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2009-06-11 21:36:02 -0400 |
| commit | 96029c4e09ccbd73a6d0ed2b29e80bf2586ad7ef (patch) | |
| tree | 032d2ac7024250c18487a2c7122af68fe56567ff /fs/open.c | |
| parent | d3ef3d7351ccfbef3e5d926efc5ee332136f40d4 (diff) | |
fs: introduce mnt_clone_write
This patch speeds up lmbench lat_mmap test by about another 2% after the
first patch.
Before:
avg = 462.286
std = 5.46106
After:
avg = 453.12
std = 9.58257
(50 runs of each, stddev gives a reasonable confidence)
It does this by introducing mnt_clone_write, which avoids some heavyweight
operations of mnt_want_write if called on a vfsmount which we know already
has a write count; and mnt_want_write_file, which can call mnt_clone_write
if the file is open for write.
After these two patches, mnt_want_write and mnt_drop_write go from 7% on
the profile down to 1.3% (including mnt_clone_write).
[AV: mnt_want_write_file() should take file alone and derive mnt from it;
not only all callers have that form, but that's the only mnt about which
we know that it's already held for write if file is opened for write]
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/open.c')
| -rw-r--r-- | fs/open.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/open.c b/fs/open.c index bdfbf03615a..7200e23d925 100644 --- a/fs/open.c +++ b/fs/open.c @@ -612,7 +612,7 @@ SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode) audit_inode(NULL, dentry); - err = mnt_want_write(file->f_path.mnt); + err = mnt_want_write_file(file); if (err) goto out_putf; mutex_lock(&inode->i_mutex); @@ -761,7 +761,7 @@ SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group) if (!file) goto out; - error = mnt_want_write(file->f_path.mnt); + error = mnt_want_write_file(file); if (error) goto out_fput; dentry = file->f_path.dentry; |