* Andrew Morton <[email protected]> wrote:
> On Thu, 26 Jul 2007 11:20:25 +0200 Ingo Molnar <[email protected]> wrote:
>
> > Once we give the kernel the knowledge that the dentry wont be used again
> > by this app, the kernel can do a lot more intelligent decision and not
> > baloon the dentry cache.
> >
> > ( we _do_ want to baloon the dentry cache otherwise - for things like
> > "find" - having a fast VFS is important. But known-use-once things
> > like the daily updatedb job can clearly be annotated properly. )
>
> Mutter. /proc/sys/vm/vfs_cache_pressure has been there for what,
> three years? Are any distros raising it during the updatedb run yet?
but ... that's system-wide, and the 'dont baloon the dcache' is only a
property of updatedb. Still, it's useful to debug this thing.
below is an updatedb hack that sets vfs_cache_pressure down to 0 during
an updatedb run. Could someone who is affected by the 'morning after'
problem give it a try? If this works then we can think about any other
measures ...
Ingo
--- /etc/cron.daily/mlocate.cron.orig
+++ /etc/cron.daily/mlocate.cron
@@ -1,4 +1,7 @@
#!/bin/sh
nodevs=$(< /proc/filesystems awk '$1 == "nodev" { print $2 }')
renice +19 -p $$ >/dev/null 2>&1
+PREV=`cat /proc/sys/vm/vfs_cache_pressure 2>/dev/null`
+echo 0 > /proc/sys/vm/vfs_cache_pressure 2>/dev/null
/usr/bin/updatedb -f "$nodevs"
+[ "$PREV" != "" ] && echo $PREV > /proc/sys/vm/vfs_cache_pressure 2>/dev/null
-
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