I'll have to see if/how this impacts the flush behavior. I don't THINK we are doing getattrs in the middle of the link, but the trace information kind of went astray when the VM's gor reverted to base OS. Also, your recommended workaround of setting no_wdelay only works if the NFS server is Linux, the option isn't available on Solaris or HP-UX. This limits it's usefulness in heterogenous environments. Solaris 10 doesn't support async NFS exports, and we've already discussed how the small-write optimization overrides write behavior on async mounts. ================================================================= 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: Brian R Cowan/Cupertino/IBM@IBMUS Cc: Carlos Carvalho <carlos@xxxxxxxxxxxxxx>, linux-nfs@xxxxxxxxxxxxxxx, linux-nfs-owner@xxxxxxxxxxxxxxx Date: 06/04/2009 04:57 PM Subject: Re: Link performance over NFS degraded in RHEL5. -- was : Read/Write NFS I/O performance degraded by FLUSH_STABLE page flushing On Thu, 2009-06-04 at 16:43 -0400, Brian R Cowan wrote: > What I'm trying to understand is why RHEL 4 is not flushing anywhere near > as often. Either RHEL4 erred on the side of not writing, and RHEL5 is > erring on the opposite side, or RHEL5 is doing unnecessary flushes... I've > seen that 2.6.29 flushes less than the Red hat 2.6.18-derived kernels, but > it still flushes a lot more than RHEL 4 does. Most of that increase is probably mainly due to the changes to the way stat() works. More precisely, it would be due to this patch: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git&a=commitdiff&h=70b9ecbdb9c5fdc731f8780bffd45d9519020c4a which went into Linux 2.6.16 in order to fix a posix compatibility issue. 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
