Re: heavy file i/o on ext3 filesystem leads to huge ext3_inode_cache and dentry_cache that doesn't return to normal for hours

[Andrew Morton <akpm@osdl.org>]

On Fri, 4 Aug 2006 09:53:14 +0200
"Maarten Maathuis" <madman2003@gmail.com> wrote:

> On 8/4/06, Dave Kleikamp <shaggy@austin.ibm.com> wrote:
> > On Thu, 2006-08-03 at 18:27 +0200, Maarten Maathuis wrote:
> > > I have a kernel specific problem and this seemed like a suitable place to ask.
> > >
> > > I would like responces to be CC'ed to me if possible.
> > >
> > > I use a 2.6.17-ck1 kernel on an amd64 system. I have observed this
> > > problem on other/older kernels.
> > >
> > > Whenever there is serious hard drive activity (such as doing "slocate
> > > -u") ext3_inode_cache and dentry_cache grow to a combined 400-500 MiB.

Increasing /proc/sys/vm/vfs_cache_pressure should increase the inode/dentry
reclaim rate.

> >
> > echo 2 > /proc/sys/vm/drop_caches
> >
> > This feature is relatively new.
> >
> 
> Thank you, i tried echo'ing a 1 into that and it had no effect iirc.

1 drops pagecache, 2 drops dentries and inodes.  Pagecache pins inodes, so
using 2 will drop less inodes than using 3.

> Documentation on /proc/sys/vm seems pretty scarce.

Documentation/filesystems/proc.txt