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/file_table.c | |
parent | d3ef3d7351ccfbef3e5d926efc5ee332136f40d4 (diff) | |
download | linux-96029c4e09ccbd73a6d0ed2b29e80bf2586ad7ef.tar.bz2 |
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/file_table.c')
-rw-r--r-- | fs/file_table.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/file_table.c b/fs/file_table.c index 54018fe48840..3d66dbcebef6 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -214,7 +214,7 @@ int init_file(struct file *file, struct vfsmount *mnt, struct dentry *dentry, */ if ((mode & FMODE_WRITE) && !special_file(dentry->d_inode->i_mode)) { file_take_write(file); - error = mnt_want_write(mnt); + error = mnt_clone_write(mnt); WARN_ON(error); } return error; |