On Sat, Jun 15, 2013 at 06:35:02AM -0400, Mark Seger wrote: > Basically everything do it with collectl, a tool I wrote and opensourced > almost 10 years ago. it's numbers are very accurate - I've compared with > iostat on numerous occasions whenever I might have had doubts and they > always agree. Since both tools get their data from the same place, > /proc/diskstats, it's hard for them not to agree AND its numbers also agree > with /proc/fs/xfs. Ok, that's all I wanted to know. > happening? > > To restate what's going on, I have a very simple script that I'm > duplicating what openstack swift is doing, namely to create a file with > mkstmp and than running an falloc against it. The files are being created > with a size of zero but it seems that xfs is generating a ton of logging > activity. I had read your posted back in 2011 about speculative > preallocation and can't help but wonder if that's what hitting me here. I > also saw where system memory can come into play and this box has 192GB and > 12 hyperthreaded cores. > > I also tried one more run without falloc, this is creating 10000 1K files, > which should be about 10MB and it looks like it's still doing 140MB of I/O > which still feels like a lot but at least it's less than the 1k files will still write 4k filesystem blocks, so there's going to be 40MB/s there at least. As it is, I ran a bunch of tests yesterday writing 4k files, and I got 180MB/s @ 32,000 files/s. That's roughly 130MB/s for data, and another 50MB/s for log and metadata traffic. But without knowing your test configuration and using your test script, I can't compare those results to yours. Can you provide the information in: http://xfs.org/index.php/XFS_FAQ#Q:_What_information_should_I_include_when_reporting_a_problem.3F > If there is anything more I can provide I'll be happy to do so. Actually I > should point out I can easily generate graphs and if you'd like to see some > examples I can provide those too. PCP generates realtime graphs, which is what I use ;) > Also, if there is anything I can report > from /proc/fs/xfs I can relatively easily do that as well and display it > side by side with the disk I/O. Let's see if there is something unusual in your setup that might explain it first... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
