Re: high load, no bottleneck

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Sat, Sep 21, 2013 at 11:44:26AM +0200, Edgar Fuß wrote:
> ED> 2908 getattr
> EF> During which timeframe?
> ED> 22.9 seconds.
> So that's >100 getattrs per second.
> 
> > Indeed [lots of 549-byte write requests] is weird.
> > But how small write could kill WAPBL performances?
> No idea. I think I'm out of luck now, but maybe it rings a bell with someone 
> else.
> 
> It would probably help finding out (with WAPL logging) how often the journal 
> flushes happen.
> 
> I myself can't make sense out of the combination of
> -- vfs.wapbl.flush_disk_cache=0 mitigating the problem
> -- neither the RAID set nor its components showing busy in iostat
> Maybe during a flush, the discs are not regarded busy?

I suspect that indeed, while a fluch cache command is running, the
disk is not considered busy. Only read and write commands are tracked.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--