Re: memory usage

[Samuel Thibault]

Samuel Thibault, le Mon 20 Aug 2007 02:06:18 +0200, a écrit :
> Hi,
> 
> Samuel Thibault, le Mon 06 Aug 2007 21:10:02 +0200, a écrit :
> > Also, something odd: say I have a big file /tmp/foo
> > 
> > $ cat /tmp/foo > /dev/null
> > ... "inactive" grows in vmstat, takes some time...
> > $ cat /tmp/foo > /dev/null
> > takes almost no time since it's all cached.
> > $ find /var -printf ""
> > ... "inactive" falls down to the original value
> > $ cat /tmp/foo > /dev/null
> > ... "inactive" grows in vmstat again, takes some time...
> > 
> > It looks like resolving directories/files entries somehow flushes out
> > the page cache.  There actually doesn't seem to be any caching for
> > directories/files: find /var/log always reads from the disk (the led
> > flashes).
> 
> I've found the "problem": vm/vm_object.c:171: 
> int             vm_object_cached_max = 200;    /* may be patched*/
> 
> Only 200 objects at a time may be held in memory. By nowadays'
> standards, that seems quite low. In the case I've raised (find /var),
> it's just not enough (the result can't fit into 200 objects).  We should
> probably raise it in debian at least.

Just as a clue: on my linux, lsof | wc -l returns 1000 without X
desktop, and 2000 with X desktop...

Samuel