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?!? ;'( (I don't know if anyone really has an answer, just wanted to rant) -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
