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Date:      Sat, 20 Oct 2012 15:45:05 -0400
From:      Outback Dingo <outbackdingo@gmail.com>
To:        Ivan Voras <ivoras@freebsd.org>
Cc:        "freebsd-hackers@freebsd.org Hackers" <freebsd-hackers@freebsd.org>, Rick Macklem <rmacklem@uoguelph.ca>, Nikolay Denev <ndenev@gmail.com>
Subject:   Re: NFS server bottlenecks
Message-ID:  <CAKYr3zzvb%2BiJzX8zmxUeH1ZjNEnc1FuuE5SdmYUAgQH84O64Mg@mail.gmail.com>
In-Reply-To: <CAF-QHFXB=yfD2EPoQf4C8YyX=0BA0Awndg0QNsWO8_rq=StHhQ@mail.gmail.com>
References:  <CAF-QHFWY0drcrUpo7GGD1zQNSDWsEeB_LHAjEbUKrX2ovQHNxw@mail.gmail.com> <191784842.2570110.1350737132305.JavaMail.root@erie.cs.uoguelph.ca> <CAF-QHFXB=yfD2EPoQf4C8YyX=0BA0Awndg0QNsWO8_rq=StHhQ@mail.gmail.com>

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On Sat, Oct 20, 2012 at 3:28 PM, Ivan Voras <ivoras@freebsd.org> wrote:
> On 20 October 2012 14:45, Rick Macklem <rmacklem@uoguelph.ca> wrote:
>> Ivan Voras wrote:
>
>>> I don't know how to interpret the rise in context switches; as this is
>>> kernel code, I'd expect no context switches. I hope someone else can
>>> explain.
>>>
>> Don't the mtx_lock() calls spin for a little while and then context
>> switch if another thread still has it locked?
>
> Yes, but are in-kernel context switches also counted? I was assuming
> they are light-weight enough not to count.
>
>> Hmm, I didn't look, but were there any tests using UDP mounts?
>> (I would have thought that your patch would mainly affect UDP mounts,
>>  since that is when my version still has the single LRU queue/mutex.
>
> Another assumption - I thought UDP was the default.
>
>>  As I think you know, my concern with your patch would be correctness
>>  for UDP, not performance.)
>
> Yes.

Ive got a similar box config here, with 2x 10GB intel nics, and 24 2TB
drives on an LSI controller.
Im watching the thread patiently, im kinda looking for results, and
answers, Though Im also tempted to
run benchmarks on my system also see if i get similar results I also
considered that netmap might be one
but not quite sure if it would help NFS, since its to hard to tell if
its a network bottle neck, though it appears
to be network related.

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