On Tue, Sep 27, 2011 at 12:49:29PM +0300, Avi Kivity wrote: > On 09/27/2011 12:00 PM, Robin Lee Powell wrote: > >On Tue, Sep 27, 2011 at 01:48:43AM -0700, Robin Lee Powell wrote: > >> On Tue, Sep 27, 2011 at 04:41:33PM +0800, Emmanuel Noobadmin wrote: > >> > On 9/27/11, Robin Lee Powell<rlpowell@xxxxxxxxxxxxxxxxxx> wrote: > >> > > On Mon, Sep 26, 2011 at 04:15:37PM +0800, Emmanuel Noobadmin > >> > > wrote: > >> > >> It's unrelated to what you're actually using as the disks, > >> > >> whether file or block devices like LVs. I think it just makes > >> > >> KVM tell the host not to cache I/O done on the storage device. > >> > > > >> > > Wait, hold on, I think I had it backwards. > >> > > > >> > > It tells the *host* to not cache the device in question, or the > >> > > *VMs* to not cache the device in question? > >> > > >> > I'm fairly certain it tells the qemu not to cache the device in > >> > question. If you don't want the guest to cache their i/o, then the > >> > guest OS should be configured if it allows that. Although I'm not > >> > sure if it's possible to disable disk buffering/caching system > >> > wide in Linux. > >> > >> OK, great, thanks. > >> > >> Now if I could just figure out how to stop the host from swapping > >> out much of the VMs' qemu-kvm procs when it has almost a GiB of RAM > >> left. -_- swappiness 0 doesn't seem to help there. > > > >Grrr. > > > >I turned swap off to clear it. A few minutes ago, this host was at > >zero swap: > > > >top - 01:59:10 up 10 days, 15:17, 3 users, load average: 6.39, 4.26, 3.24 > >Tasks: 151 total, 1 running, 150 sleeping, 0 stopped, 0 zombie > >Cpu(s): 6.6%us, 1.0%sy, 0.0%ni, 85.9%id, 6.3%wa, 0.0%hi, 0.2%si, 0.0%st > >Mem: 8128772k total, 6511116k used, 1617656k free, 14800k buffers > >Swap: 8388604k total, 672828k used, 7715776k free, 97536k cached > > > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > > 2504 qemu 20 0 2425m 1.8g 448 S 10.0 23.4 3547:59 qemu-kvm > > 2258 qemu 20 0 2425m 1.7g 444 S 2.7 21.7 1288:15 qemu-kvm > >18061 qemu 20 0 2433m 1.8g 428 S 2.3 23.4 401:01.99 qemu-kvm > >10335 qemu 20 0 1864m 861m 456 S 1.0 10.9 2:04.26 qemu-kvm > >[snip] > > > >Why is it doing this?!? ;'( > > > > Please post the contents of /proc/meminfo and /proc/zoneinfo when > this is happening. I just noticed that the amount of RAM the VMs had in VIRT added up to considerably more than the host's actual RAM; hard_limit is now on. So I may not be able to replicate this. :) -Robin -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
