[Qemu-devel] Question about posixaio thread number.
Hi Anthony, I started a guest with cache=none and aio=threads When i did some io tests in Guest say dd like dd if=/dev/zero oflag=direct of=/mnt/sdb1/date.img bs=4k count=262114 qemu will start one or several threads to perform IO requests. It seems qemu makes use of its own posixaio. I'm wondering how qemu decides how many threads should be created to perform io operation? Thanks, Gui
[Qemu-devel] Question about posixaio thread number.
Hi Anthony, I started a guest with cache=none and aio=threads When i did some io tests in Guest say dd like dd if=/dev/zero oflag=direct of=/mnt/sdb1/date.img bs=4k count=262114 qemu will start one or several threads to perform IO requests. It seems qemu makes use of its own posixaio. I'm wondering how qemu decides how many threads should be created to perform io operation? Thanks, Gui
Re: [Qemu-devel] [RFC] block I/O throttling: how to enable in libvirt
On 2011-9-1 16:11, Stefan Hajnoczi wrote: > On Thu, Sep 01, 2011 at 01:05:31PM +0800, Zhi Yong Wu wrote: >> On Wed, Aug 31, 2011 at 08:18:19AM +0100, Stefan Hajnoczi wrote: >>> On Tue, Aug 30, 2011 at 2:46 PM, Adam Litke wrote: On Tue, Aug 30, 2011 at 09:53:33AM +0100, Stefan Hajnoczi wrote: > I/O throttling can be applied independently to each -drive attached to > a guest and supports throughput/iops limits. For more information on > this QEMU feature and a comparison with blkio-controller, see Ryan > Harper's KVM Forum 2011 presentation: > http://www.linux-kvm.org/wiki/images/7/72/2011-forum-keep-a-limit-on-it-io-throttling-in-qemu.pdf From the presentation, it seems that both the cgroups method the the qemu method offer comparable control (assuming a block device) so it might possible to apply either method from the same API in a transparent manner. Am I correct or are we suggesting that the Qemu throttling approach should always be used for Qemu domains? >>> >>> QEMU I/O throttling does not provide a proportional share mechanism. >>> So you cannot assign weights to VMs and let them receive a fraction of >>> the available disk time. That is only supported by cgroups >>> blkio-controller because it requires a global view which QEMU does not >>> have. >>> >>> So I think the two are complementary: >>> >>> If proportional share should be used on a host block device, use >>> cgroups blkio-controller. >>> Otherwise use QEMU I/O throttling. >> Stefan, >> >> Do you agree with introducing one new libvirt command blkiothrottle now? >> If so, i will work on the code draft to make it work. > > No, I think that the blkiotune command should be extended to support > QEMU I/O throttling. This is not new functionality, we already have > cgroups blkio-controller support today. Therefore I think it makes > sense to keep a unified interface instead of adding a new command. Agreed. Proportional controlling interfaces and throttling interfaces are all the same cgroup subsystem. So Just extend blkiotune to add new options to support throttling tuning. Thanks, Gui > > Stefan > >
Re: [Qemu-devel] [PATCH 00/26] q35 chipset support for native pci?express support
Hi Yamahata I'm wondering if there're any PCI-e device emulated by QEmu? And I think the hogplug patches are in this repo, right? Thanks, Gui Isaku Yamahata wrote: > Okay. Can you please try git clone again? > > On Wed, Apr 20, 2011 at 06:41:56PM -0500, Adnan Khaleel wrote: >> Something is still wrong, >> >> I get the following errors now: >> >> : >> error: cannot unpack fffd440d2ca664a03ee83eabc00107eaf74d7af4 from /users/ >> akhaleel/akhaleel/MergeSpace/qemu_0.14_q35/qemu/.git/objects/pack/ >> pack-c0c6d1b7fc8ae79abf99bfb6a402b50e2ec98557.pack >> error: Unable to find ad620c29c2da573e3a5f13f5b1eb2694fee64cfb under http:// >> people.valinux.co.jp/~yamahata/qemu/q35/20110316/qemu/ >> Cannot obtain needed none ad620c29c2da573e3a5f13f5b1eb2694fee64cfb >> while processing commit . >> rm: cannot remove directory >> `/users/akhaleel/akhaleel/MergeSpace/qemu_0.14_q35/ >> qemu/.git/clone-tmp': Directory not empty >> >> Adnan >> >> >> ━ >> From: Isaku Yamahata [mailto:yamah...@valinux.co.jp] >> To: Hu Tao [mailto:hu...@cn.fujitsu.com], Adnan Khaleel >> [mailto:ad...@khaleel.us] >> Cc: qemu-devel@nongnu.org >> Sent: Wed, 20 Apr 2011 17:46:44 -0500 >> Subject: Re: [Qemu-devel] [PATCH 00/26] q35 chipset support for native >> pci >> express support >> >> I forgot to changet its HEAD. Now it's fixed. >> So please change the branch manually or clone the repo again. >> >> On Tue, Apr 19, 2011 at 04:58:32PM +0800, Hu Tao wrote: >> > On Tue, Apr 19, 2011 at 05:51:27PM +0900, Isaku Yamahata wrote: >> > > On Tue, Apr 19, 2011 at 04:28:01PM +0800, Hu Tao wrote: >> > > > On Wed, Mar 16, 2011 at 06:29:11PM +0900, Isaku Yamahata wrote: >> > > > > This patch series adds basic q35 chipset support for native pci >> express >> > > > > support. Some bios related patches are still needed. >> > > > > For those who want to try it, the following repo is avaiable. >> > > > > (vgabios doesn't need patches, so use the upstream one) >> > > > > >> > > > > git clone >> http://people.valinux.co.jp/~yamahata/qemu/q35/20110316/ >> qemu >> > > > > git clone >> http://people.valinux.co.jp/~yamahata/qemu/q35/20110316/ >> seabios >> > > > >> > > > Hi, >> > > > >> > > > When I visit the links, the pages say 'You dont have permission'. >> Could >> > > > you make these git-repos avaiable again? Thanks in advance. >> > > >> > > The link is not for human-reading. Just issue the git command. >> > >> > Done. Thanks:) >> > >> > > -- >> > > yamahata >> > >> >> -- >> yamahata >> >
