In CGG we have had some more progress with our investigations into poor IO performance with small IO sizes using Lustre 1.4.6/x and 1.4.7.x and we created a new bug on this issue which I shall summarise here.
Our clients are RHEL3.4 kernel 2.4.21 and we believe the issue is due to ll_writepage being called by the kernel vm daemons to release vm cache memory too aggressively, this results in the cache being flushed within a few milliseconds of being written so small IO's are not aggregated into large rpcs. We had some success in tuning the vm tunables but the problem comes back at some point later. There may be some later 2.4 vm patches we can apply or we may just use a 2.6 kernel which does not seem to suffer from the same problems. J Belshaw CGG Redhill -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Peter Bojanic Sent: 15 November 2006 17:36 To: Richard Shane Canon Cc: [email protected] Subject: [Lustre-discuss] Read performance issues at ORNL Shane, Regarding the read performance issues you mentioned today, could you take a look at this bug, resolved in Lustre 1.4.7, to see if it resembles the problem you're seeing: https://bugzilla.clusterfs.com/show_bug.cgi?id=10265 I've heard a few reports today at SC about slow read performance use cases in 1.4.6 and 1.4.7, which I'd like to get on top of immediately. If this is not a match for your case, please file a Bugzilla ticket and let me know the number. I'd like to hand this off promptly to a senior IO specialist. Thanks, Peter _______________________________________________ Lustre-discuss mailing list [email protected] https://mail.clusterfs.com/mailman/listinfo/lustre-discuss _______________________________________________ Lustre-discuss mailing list [email protected] https://mail.clusterfs.com/mailman/listinfo/lustre-discuss
