Messages in this thread Patch in this message | | | Date | Fri, 21 Feb 2003 12:20:24 -0800 | From | Andrew Morton <> | Subject | Re: Strange performance change 59 -> 61/62 |
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"Martin J. Bligh" <mbligh@aracnet.com> wrote: > > >> Some more stats ... which look rather suspicious. 600% increase for > >> dentry_open and __mark_inode_dirty? Hmmmmm. > > > > __mark_inode_dirty() just got itself an smp_mb(). Would be instructive to > > disable that. > > > > dentry_open(): don't know - fs/open.c hasn't changed at all. Perhaps > > dcache_rcu has caused additional pingpong? > > 2.5.59-mjb6 84 __mark_inode_dirty > 2.5.61-mjb1 594 __mark_inode_dirty > 2.5.61-mjb1-no_mb 74 __mark_inode_dirty > > Yup, that fixed that one ... but presumably it was put there for a reason, > so I can't just rip it out ;-) Thanks, I'll go take a closer look at the > others.
mark_inode_dirty() tends to be called _very_ frequently. Too frequently.
Could you try remounting all filesystems noatime with
mount /mnt/point -o remount,noatime
and the below patch will prevent us calling the barrier-happy current_kernel_time() for noatime mounts.
diff -puN fs/inode.c~update_atime-speedup fs/inode.c --- 25/fs/inode.c~update_atime-speedup Fri Feb 21 12:17:00 2003 +++ 25-akpm/fs/inode.c Fri Feb 21 12:17:33 2003 @@ -1091,17 +1091,20 @@ sector_t bmap(struct inode * inode, sect void update_atime(struct inode *inode) { - struct timespec now = CURRENT_TIME; + struct timespec now; - /* Can later do this more lazily with a per superblock interval */ - if (timespec_equal(&inode->i_atime, &now)) - return; if (IS_NOATIME(inode)) return; if (IS_NODIRATIME(inode) && S_ISDIR(inode->i_mode)) return; if (IS_RDONLY(inode)) return; + + now = CURRENT_TIME; + + /* Can later do this more lazily with a per superblock interval */ + if (timespec_equal(&inode->i_atime, &now)) + return; inode->i_atime = now; mark_inode_dirty_sync(inode); } _
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