Date: Fri, 20 Aug 1999 13:32:17 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: "Matthew D. Fuller" <fullermd@futuresouth.com> Cc: Steve Ames <steve@cioe.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: Async NFS exports? Message-ID: <199908202032.NAA64957@apollo.backplane.com> References: <199908201813.NAA66892@ns1.cioe.com> <19990820150744.G2131@futuresouth.com>
next in thread | previous in thread | raw e-mail | index | archive | help
:> 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?
:
:As a first guess, probably not unless you have a large number of active
:clients. Any modern hard disc will outperform ethernet/fast ethernet,
:especially for larger read/writes. For large numbers of smaller
:operations, or when there is a large number of simultaneous outstanding
:requests from clients, maybe. I'd say watch the disc itself (iostat is
:your friend), and if it's pegged (especially large numbers of tps) async
:might buy you some increase.
:--
:Matthew Fuller (MF4839) | fullermd@over-yonder.net
Not much if at all, whether you have a large number of clients or not,
at least if you are using NFSv3 mounts.
The reason is due to the way NFSv3 issues writes. NFSv3 issues a
write but no longer assumes that the write has been synced to the
server's disk as of when the reply comes back. Instead it keeps the
buffer around and does a later commit rpc to do the sync, presumably
long after the server has already synced the data.
So, effectively, all NFSv3 writes are async insofar as the client's
buffer cache is able to keep abrest of the write-rate.
Hmm, interesting. I see another optimization I can do to fix the
buffer cache saturation case in CURRENT on the client. The COMMIT rpc's
aren't being issued async.
-Matt
Matthew Dillon
<dillon@backplane.com>
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199908202032.NAA64957>