On Sat, May 30, 2009 at 10:26 PM, Trond Myklebust <trond.myklebust@xxxxxxxxxx> wrote: > On Sat, 2009-05-30 at 10:22 +1000, Greg Banks wrote: >> On Sat, May 30, 2009 at 3:35 AM, Trond Myklebust >> <trond.myklebust@xxxxxxxxxx> wrote: >> > On Fri, 2009-05-29 at 13:25 -0400, Brian R Cowan wrote: >> >> >> > > Firstly, the server only uses O_SYNC if you turn off write gathering > (a.k.a. the 'wdelay' option). The default behaviour for the Linux nfs > server is to always try write gathering and hence no O_SYNC. Well, write gathering is a total crock that AFAICS only helps single-file writes on NFSv2. For today's workloads all it does is provide a hotspot on the two global variables that track writes in an attempt to gather them. Back when I worked on a server product, no_wdelay was one of the standard options for new exports. > Secondly, even if it were the case, then this does not justify changing > the client behaviour. I totally agree, it was just an observation. In any case, as Christoph points out, the ext3 performance difference makes an unstable WRITE+COMMIT slower than a stable WRITE, and you already assumed that. -- Greg. -- 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
