Personally, I would leave the default export options alone. Simply because they more or less match the defaults for the other NFS servers. Also, there may be negative impacts of changing the default export option to no_wdelay on really busy servers. One possible result is that more CPU time gets spent waiting on writes to disk. I'm a bit paranoid when it comes to tuning *server* settings, since they impact all clients all at once, where client tuning generally only impacts the one client. ================================================================= Brian Cowan Advisory Software Engineer ClearCase Customer Advocacy Group (CAG) Rational Software IBM Software Group 81 Hartwell Ave Lexington, MA Phone: 1.781.372.3580 Web: http://www.ibm.com/software/rational/support/ Please be sure to update your PMR using ESR at http://www-306.ibm.com/software/support/probsub.html or cc all correspondence to sw_support@xxxxxxxxxx to be sure your PMR is updated in case I am not available. From: Trond Myklebust <trond.myklebust@xxxxxxxxxx> To: Steve Dickson <SteveD@xxxxxxxxxx> Cc: Neil Brown <neilb@xxxxxxx>, Greg Banks <gnb@xxxxxxxx>, Brian R Cowan/Cupertino/IBM@IBMUS, linux-nfs@xxxxxxxxxxxxxxx Date: 06/05/2009 08:48 AM Subject: Re: Link performance over NFS degraded in RHEL5. -- was : Read/Write NFS I/O performance degraded by FLUSH_STABLE page flushing On Fri, 2009-06-05 at 07:35 -0400, Steve Dickson wrote: > Brian R Cowan wrote: > > Trond Myklebust <trond.myklebust@xxxxxxxxxx> 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... It dates back to the days when most Linux clients in use in the field were NFSv2 only. After all, it has only been 15 years... Trond -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
