(adding back the kvm mailing list) On Tue, Jul 14, 2015 at 1:12 AM, "C. Bröcker" <c.broc...@intercollect.com> wrote: > On 14-7-2015 10:04, Hansa wrote: >> >> On 13-7-2015 20:57, David Matlack wrote: >>> >>> On Thu, Jun 18, 2015 at 10:26 AM, David Matlack <dmatl...@google.com> >>> wrote: >>>> >>>> On Thu, Jun 18, 2015 at 1:25 AM, Hansa <for...@logic-q.nl> wrote: >>>>> >>>>> Hi, >>>>> >>>>> I have a LAMP server as guest in KVM. Whenever the server is idle for >>>>> some >>>>> time it takes about 30 seconds to load a Wordpress site. >>>>> If the server is not idle the site shows up in max 5 seconds. I've >>>>> already >>>>> turned of power management in the guest by passing >>>>> >>>>> GRUB_CMDLINE_LINUX_DEFAULT="apm=off" >>>>> >>>>> in /etc/default/grub. This has no effect. >>>>> Does KVM do some power management on guests? If so, how do I turn this >>>>> off >>>>> for my LAMP guest? >>>> >>>> KVM doesn't do any power management of guests. But if everything is idle >>>> on >>>> the host (including your guest), then host power management could kick >>>> in. >>>> Have you tried playing with host pm? >>>> >>>> Could you try running your workload with the guest kernel parameter >>>> "idle=poll" >>>> and let me know the performance? >>>> >>>> Also, if you are running Linux 4.0 or later on the host, could you try >>>> running >>>> your workload with the KVM module parameter "halt_poll_ns=500000"? >>> >>> Hansa-- Did you ever get a chance to run your workload with these >>> changes? >> >> Hi David, >> >> Sorry I didn't respond to your mail earlier and nice of you to check back. >> To be honest no I haven't. To much work overload on my side. I've just added >> the idle=poll to the guests' grub and rebooted the server. I'll let it run a >> few day's to check if it helps. Btw: I'm running 2.6 linux kernel here so >> I'm not sure if I can add the "halt_poll_ns" param to KVM. >> >> Best, Hansa > > Wow! That makes real difference! > The site was never that fast! Although CPU load is constantly on 100% any > chance I can tweak this param? And is there a similar param for Windows > guests?
Since idle=poll gave a noticeable improvement, your workload is a good candidate for halt_poll_ns. This is a host KVM module parameter. It will give you a similar speedup, it will work independent of your guest os, and won't peg your cpu usage at 100% during periods of no activity. If you don't have halt_poll_ns available (your host kernel older than 4.0), is upgrading to a newer kernel or backporting the patch [1] an option? I'm not sure of any more guest params you can tweak (linux or windows), but I'll let you know if I come up with anything. [1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=f7819512996361280b86259222456fcf15aad926 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
