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Date:      Fri, 20 Aug 1999 15:06:53 -0700 (PDT)
From:      Matthew Dillon <dillon@apollo.backplane.com>
To:        Steve Ames <steve@cioe.com>
Cc:        freebsd-hackers@FreeBSD.ORG
Subject:   Re: Async NFS exports?
Message-ID:  <199908202206.PAA65547@apollo.backplane.com>
References:   <199908201813.NAA66892@ns1.cioe.com>

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:I asked this on stable but didn't get a response... Would I get any
:performance increases by mounting NFS exported partition as Async?
:
:Would my soul be tormented in purgatory for doing it?
:
:Just to be clear... I am wondering if mounting (on the NFS _server_) a
:partition (that is exportable) as async will have any performance 
:benefits to the NFS clients?
:
:-Steve

    Ok, I've run some more tests.  Basically you want to run NFSv3 under
    CURRENT and you want to run at least 3 nfsiod's.  On a 100BaseTX network
    this will give you unsaturated write performance in the ballpark of
    9 MBytes/sec.  Saturated write performance, that is where you write more
    then the client-side buffer cache can handle, will stabilize at
    2.5 MBytes/sec.  I have a patch for CURRENT which will increase the
    saturated write performance to 4.5 MBytes/sec (basically by moving the
    nfs_commit() from nfs_writebp() to nfs_doio() so it can be asynchronized).
    Hopefully that patch will go in soon but there's a pretty big backlog of
    patches that haven't gone in yet, some over a week and a half old, so...

    In anycase, even without the patch if you run a couple of nfsiod's and
    do not saturated the buffer cache you should get optimal performance.

    Backing-porting the patch for nfs_commit to STABLE is possible but is
    not likely to help much because the major performance restriction in
    STABLE is related to buffer cache management, not NFS.


    OS		#nfsiod's	unsaturated	saturated
				write perf.	write perf.
				( ..... 100BASETX ...... )

    CURRENT	0		9 MBytes/sec	2.5 MBytes/sec
    CURRENT	4		9 MBytes/sec	4.5 MBytes/sec(w/patch)

    STABLE	0		3 MBytes/sec	3 MBytes/sec(1)
    STABLE	4		4 MBytes/sec	3 MBytes/sec(1)

	note(1): saturated performance under STABLE is extremely inconsistant

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>



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