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Date:      Fri, 22 Jul 2011 13:41:34 -0700
From:      pete wright <nomadlogic@gmail.com>
To:        "Michael W. Lucas" <mwlucas@blackhelicopters.org>
Cc:        questions@freebsd.org, Mike Tancsa <mike@sentex.net>
Subject:   Re: em0 NIC slow on 8.2-p1 amd64?
Message-ID:  <CAGBmCT54UfvjqDzuXRtbd6jHEvWVV-gitnhTLqz4fLoX4aqOxw@mail.gmail.com>
In-Reply-To: <20110722202635.GA57111@bewilderbeast.blackhelicopters.org>
References:  <20110721141011.GB47190@bewilderbeast.blackhelicopters.org> <20110721151210.GA47663@bewilderbeast.blackhelicopters.org> <4E29BC1F.6060103@sentex.net> <20110722190821.GA55040@bewilderbeast.blackhelicopters.org> <4E29D37E.8070908@sentex.net> <20110722201034.GA56830@bewilderbeast.blackhelicopters.org> <4E29DA4F.9010006@sentex.net> <20110722202635.GA57111@bewilderbeast.blackhelicopters.org>

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On Fri, Jul 22, 2011 at 1:26 PM, Michael W. Lucas
<mwlucas@blackhelicopters.org> wrote:
> On Fri, Jul 22, 2011 at 04:15:11PM -0400, Mike Tancsa wrote:
>> On 7/22/2011 4:10 PM, Michael W. Lucas wrote:

> Will applications such as NFS cut bandwith usage that much?
>
I have seen similar performance degradations with NFS in the past.  I
have seem cases where throughput is hurt due to frequent getattr()
calls by the NFS client (esp noticable on Linux hosts traversing large
namespaces fwiw).

Some possible workarounds/tweaks:
1) increase rsize/wsize (32k for larger files for example) of client mount
2) if performance is only requirement UDP will increase performance
versus TCP with obvious downside of using UDP :)
3) jumbo frames (MTU=9000) should help in most cases if available

I've also done a bit of testing with NFSv4 - and I find performance
here can be a bit better than v3 due to better attribute caching
(decreasing amount of getattr() calls when traversing filesystems) and
other interesting bigs v4 has.  Granted moving from v3 to v4 is not
trivial...


just my two bits :)
-pete


-- 
pete wright
www.nycbug.org



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