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Date: Tue, 26 Jul 2005 15:31:38 -0400
From: Sonny Rao <sonny@burdell.org>
To: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Andrew Morton <akpm@osdl.org>, lkml <linux-kernel@vger.kernel.org>,
       linux-mm <linux-mm@kvack.org>
Subject: Re: Memory pressure handling with iSCSI
Message-ID: <20050726193138.GA32324@kevlar.burdell.org>
References: <1122399331.6433.29.camel@dyn9047017102.beaverton.ibm.com> <20050726111110.6b9db241.akpm@osdl.org> <1122403152.6433.39.camel@dyn9047017102.beaverton.ibm.com>
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On Tue, Jul 26, 2005 at 11:39:11AM -0700, Badari Pulavarty wrote:
> On Tue, 2005-07-26 at 11:11 -0700, Andrew Morton wrote:
> > Badari Pulavarty <pbadari@us.ibm.com> wrote:
> > >
> > > After KS & OLS discussions about memory pressure, I wanted to re-do
> > >  iSCSI testing with "dd"s to see if we are throttling writes.  
> > > 
> > >  I created 50 10-GB ext3 filesystems on iSCSI luns. Test is simple
> > >  50 dds (one per filesystem). System seems to throttle memory properly
> > >  and making progress. (Machine doesn't respond very well for anything
> > >  else, but my vmstat keeps running - 100% sys time).
> > 
> > It's important to monitor /proc/meminfo too - the amount of dirty/writeback
> > pages, etc.
> > 
> > btw, 100% system time is quite appalling.  Are you sure vmstat is telling
> > the truth?  If so, where's it all being spent?
> > 
> > 
> 
> Well, profile doesn't show any time in "default_idle". So
> I believe, vmstat is telling the truth.

Badari,

You probably covered this, but just to make sure, if you're on a
pentium4 machine, I usually boot w/ "idle=poll" to see proper idle
reporting because otherwise the chip will throttle itself back and
idle time will be skewed -- at least on oprofile.

Sonny