[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] 4.2.1: Poor write performance for DomU.
On 20/02/2013 7:26 PM, Roger Pau Monné wrote: On 20/02/13 03:10, Steven Haigh wrote:Hi guys, Firstly, please CC me in to any replies as I'm not a subscriber these days. I've been trying to debug a problem with Xen 4.2.1 where I am unable to achieve more than ~50Mb/sec sustained sequential write to a disk. The DomU is configured as such:Since you mention 4.2.1 explicitly, is this a performance regression from previous versions? (4.2.0 or the 4.1 branch) This is actually a very good question. I've reinstalled my older packages of Xen 4.1.3 back on the system. Rebooting into the new hypervisor, then starting the single DomU again. Ran bonnie++ again on the DomU: Version 1.96 ------Sequential Output------ --Sequential Input- --Random- Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP zeus.crc.id.au 2G 658 97 54893 9 40845 10 1056 97 280453 33 561.2 13 Latency 27145us 426ms 257ms 31900us 24701us 222ms Version 1.96 ------Sequential Create------ --------Random Create-------- zeus.crc.id.au -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 19281 52 +++++ +++ +++++ +++ 24435 66 +++++ +++ +++++ +++ Latency 22860us 182us 706us 14803us 28us 300us Still around 50Mb/sec - so this doesn't seem to be a regression, but something else? ~50Mb/sec write, ~267Mb/sec read. Not so awesome.We are currently working on improving the speed of pv block drivers, I will look into this difference between the read/write speed, but I would guess this is due to the size of the request/ring. I would assume this would be in the DomU kernel? -- Steven Haigh Email: netwiz@xxxxxxxxx Web: http://www.crc.id.au Phone: (03) 9001 6090 - 0412 935 897 Fax: (03) 8338 0299 Attachment:
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