Re: Link performance over NFS degraded in RHEL5. -- was : Read/Write NFS I/O performance degraded by FLUSH_STABLE page flushing

Steve Dickson
2009-06-05T11:38:06Z

Brian R Cowan wrote:
> Trond Myklebust <trond.myklebust@fys.uio.no> wrote on 06/04/2009 02:04:58
> PM:
>
>> Did you try turning off write gathering on the server (i.e. add the
>> 'no_wdelay' export option)? As I said earlier, that forces a delay of
>> 10ms per RPC call, which might explain the FILE_SYNC slowness.
>
> Just tried it, this seems to be a very useful workaround as well. The
> FILE_SYNC write calls come back in about the same amount of time as the
> write+commit pairs... Speeds up building regardless of the network
> filesystem (ClearCase MVFS or straight NFS).

Does anybody had the history as to why 'no_wdelay' is an
export default? As Brian mentioned later in this thread
it only helps Linux servers, but that's good thing, IMHO. ;-)

So I would have no problem changing the default export
options in nfs-utils, but it would be nice to know why
it was there in the first place...

Neil, Greg??

steved.