A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-29 11:11:45 -04:00
Code Issues Projects Releases Packages Wiki Activity

fs: introduce mnt_clone_write

Browse source 
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 <[email protected]>
Signed-off-by: Nick Piggin <[email protected]>
Signed-off-by: Al Viro <[email protected]>
This commit is contained in:
[email protected] 2009-04-26 20:25:55 +10:00 • committed by Al Viro
commit 96029c4e09
6 changed files with 50 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

4
fs/xattr.c
View file

@ -297,7 +297,7 @@ SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
return error;
dentry = f->f_path.dentry;
audit_inode(NULL, dentry);
error = mnt_want_write(f->f_path.mnt);
error = mnt_want_write_file(f);
if (!error) {
error = setxattr(dentry, name, value, size, flags);
mnt_drop_write(f->f_path.mnt);
@ -524,7 +524,7 @@ SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
return error;
dentry = f->f_path.dentry;
audit_inode(NULL, dentry);
error = mnt_want_write(f->f_path.mnt);
error = mnt_want_write_file(f);
if (!error) {
error = removexattr(dentry, name);
mnt_drop_write(f->f_path.mnt);