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

[Steve Dickson <SteveD@redhat.com>]

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.