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From Aaron Bannert <>
Subject Re: FreeBSD load statistics.
Date Fri, 11 Jan 2002 00:06:40 GMT
On Thu, Jan 10, 2002 at 03:58:37PM -0800, Justin Erenkrantz wrote:
> On Wed, Jan 09, 2002 at 11:55:21PM -0800, Brian Pane wrote:
> > My hypothesis upon seeing these numbers is that the high run queue length
> > is due to us hitting some bottleneck in the kernel on daedalus--and because
> > post-2.0.28 releases waste less time in usr-space code between syscalls,
> > they hit that kernel bottleneck a lot harder than 2.0.28 did.
> Yes, that is my current thought.  From everything I can tell, 
> post-2.0.28 is far superior than 2.0.28.
> FWIW, Aaron was telling me that he remembers seeing high run-queue
> lengths on machines with failing hard drives.  Can anyone reproduce
> this behavior (high run-queue with idle CPU) on any other machines?
> Perhaps we could perform some testing on icarus (which should be a
> daedalus clone).
> It seems I'm not reproducing this.  We won't be able to resolve 
> any problem unless we can reproduce this in controlled 
> environments.  *sigh*  -- justin

Another thing that was brought up yesterday at dinner was the fact
that Daedalus underwent a system upgrade to 4.5. AIUI this also means
that things like libc and gcc were updated, and means that 2.0.28 and
2.0.30 were compiled by different compilers. Perhaps we should recompile
2.0.28 under the new environment and see if the load spikes are still
not happening. That would at least exclude the possibilitity that this
was introduced by the compiler and/or libraries as part of the upgrade.


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