Hills, Steve
2010-Sep-28 21:53 UTC
[Xen-users] Xen domU physical partition disk I/O write throughput %50 slower
dom0 is SLES 11 SP1, domU''s are paravirtualized SLES 10/11. Local physical disk partition attached to domU via "phy:" (3 SAS disks in RAID1+). Write throughput is %50 less than compared to write throughput to the same partition from domU. Read throughput is roughly equivalent. Tested via bonnie (e.g. with data size x2 phy mem) and "dd conv=fdatasync" where the partition is empty (no files). The domU cpu usage is small during the tests. I''ve played around with the "Xen best practices", various memory/cpu sizes with dom0/domU, elevator=noop, but there is always a %50 difference. The question is how do I eliminate/find the bottleneck? I don''t see any way to tweak the Xen split drivers/hypervisor in regards to block I/O. Thanks, Steve Hills Teradata Corporation steve.hills@teradata.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
khris4
2010-Sep-29 03:25 UTC
[Xen-users] Re: Xen domU physical partition disk I/O write throughput %50 slower
Can you provide us with some statistics. -- View this message in context: http://xen.1045712.n5.nabble.com/Xen-domU-physical-partition-disk-I-O-write-throughput-50-slower-tp2896613p2952475.html Sent from the Xen - User mailing list archive at Nabble.com. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hills, Steve
2010-Sep-29 17:45 UTC
RE: [Xen-users] Re: Xen domU physical partition disk I/O write throughput %50 slower
Note: the bonnie run was from a different time than the dd run but the difference is still 40%-50%. ----- From dom0 (2G mem) bonnie -s 4096 Bonnie 1.4: File ''./Bonnie.14020'', size: 4294967296, volumes: 1 Writing with putc()... done: 63109 kB/s 160.1 %CPU Rewriting... done: 34731 kB/s 4.0 %CPU Writing intelligently... done: 91248 kB/s 10.6 %CPU Reading with getc()... done: 58771 kB/s 105.3 %CPU Reading intelligently... done: 100379 kB/s 4.5 %CPU time dd if=/dev/zero of=test bs=1K count=1048576 conv=fdatasync 1048576+0 records in 1048576+0 records out 1073741824 bytes (1.1 GB) copied, 16.9593 s, 63.3 MB/s real 0m17.162s user 0m0.356s sys 0m4.344s ----- From domU (2G mem) bonnie -s 4096 Bonnie 1.4: File ''./Bonnie.2089'', size: 4294967296, volumes: 1 Writing with putc()... done: 47753 kB/s 57.6 %CPU Rewriting... done: 25996 kB/s 2.8 %CPU Writing intelligently... done: 50126 kB/s 7.3 %CPU Reading with getc()... done: 69383 kB/s 70.4 %CPU Reading intelligently... done: 101596 kB/s 5.0 %CPU time dd if=/dev/zero of=test bs=1K count=1048576 conv=fdatasync 1048576+0 records in 1048576+0 records out 1073741824 bytes (1.1 GB) copied, 26.6137 s, 41.9 MB/s real 0m25.741s user 0m0.512s sys 0m6.500s Steve Hills Teradata Corporation steve.hills@teradata.com -----Original Message----- From: xen-users-bounces@lists.xensource.com [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of khris4 Sent: Tuesday, September 28, 2010 8:25 PM To: xen-users@lists.xensource.com Subject: [Xen-users] Re: Xen domU physical partition disk I/O write throughput %50 slower Can you provide us with some statistics. -- View this message in context: http://xen.1045712.n5.nabble.com/Xen-domU-physical-partition-disk-I-O-wr ite-throughput-50-slower-tp2896613p2952475.html Sent from the Xen - User mailing list archive at Nabble.com. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users