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Re: NFS server responsiveness
- To: misc_(_at_)_openbsd_(_dot_)_org
- Subject: Re: NFS server responsiveness
- From: Joachim Schipper <j_(_dot_)_schipper_(_at_)_math_(_dot_)_uu_(_dot_)_nl>
- Date: Sat, 15 Apr 2006 18:19:51 +0200
- Mail-followup-to: misc_(_at_)_openbsd_(_dot_)_org
On Sat, Apr 15, 2006 at 08:31:18AM -0600, David Wilk wrote:
> I've got a test server with OpenBSD-3.8 on it (GENERIC except with
> RAIDFRAME support) and considering the hardware, it does pretty well
> with NFS performance. However, I've noticed that when under heavy NFS
> load, it becomes nearly unresponsive. Shell sessions take 2-6 seconds
> to respond, and top updates stretch out for several seconds as well.
> Is this normal behavior (trading latency for throughput)? or is there
> something else going on? Are there common pitfalls with regard to
> OpenBSD kernel tuning and latency?
I don't know about NFS, especially, but it is a common pattern that very
heavy disk activity causes responsiveness to lessen quite a bit.
ISTR reading somewhere that such behaviour is indirectly linked to the
fact that OpenBSD does not support kernel threads. However, I'm not even
sure if the latter is still true...
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