[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Read Performance issue when Xen Hypervisor is activated
[Cc-ing someone which have done disk benchmark in somewhat recent time] On Tue, 2016-12-27 at 14:26 +0000, Michael Schinzel wrote: > We have searched in the last days more and more for the cause of this > performance issue. > > In cooperation with the datacenter, we change some hardware to check, > if the problem already proceeds. We put the RAID Controller included > all RAID Arrays to another Supermicro Mainboard: X10SLM-F with only > one CPU. The result was, we got 400 MB/s read Speed. So it seems > there is an issue with the Servers Mainboard / CPU and the Xen > Hypervisor but, we also change the Mainboard to an Supermicro X9DR3-F > with the actual BIOS Version 3.2a – these also do not solved the > problem with the performance. > > What we also have done: > - Upgraded Hypervisor from default Debian 8 – 4.4.1 to 4.8. > - Tested some kernel boot configurations\ > I think it would be useful to know more about your configuration, e.g., are these tests being done in Dom0? How many vCPUs and memory does Dom0 have? > With an non hypervisor Kernel, the system also uses the read Cache of > the controller and after some read operations at the same file, it > gets 1.2 G/s back from the Cache. At Xen Hypervisor Kernel, it seems > the system do not use any caching operations. I also tested a bit > with hdparm: > > root@v7:~# hdparm -Tt /dev/sdb > > /dev/sdb: > Timing cached reads: 14060 MB in 1.99 seconds = 7076.16 MB/sec > Timing buffered disk reads: 304 MB in 3.01 seconds = 100.85 MB/sec > > This Performance is horrable. It is a RAID 10 with read/write cache > and SSD Caching functions. > > Does somebody know how Xen proceeds with such Caching Systems? > > > Yours sincerely > > Michael Schinzel -- <<This happens because I choose it to happen!>> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) Attachment:
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