Re: [PATCH 0/3] Emulate MSI-X mask bits for assigned devices
On Friday 01 October 2010 00:44:51 Marcelo Tosatti wrote: On Tue, Sep 28, 2010 at 05:44:09PM +0800, Sheng Yang wrote: Hi Avi Marcelo This patchset would add emulation of MSI-X mask bit for assigned devices in QEmu. BTW: We are also purposed an acceleration of MSI-X mask bit for KVM - to get it done in kernel. That's because sometime MSI-X mask bit was accessed very frequently by guest and emulation in QEmu cost a lot(tens to hundreds percent CPU utilization sometime), e.g. guest using Linux 2.6.18 or under some heavy workload. The method has been proved efficient in Xen, but it would require VMM to handle MSI-X table. Is that OK with you? It would be good to understand where that cost is, before. Eg. do you commit kvm irq route frequently when guest unmasks? I don't think it would cause performance issue, but maybe need another bulk of codes in kernel. I would post the in-kernel patch later, which is easier for discuss. :) -- regards Yang, Sheng -- 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
Re: [PATCH 0/3] Emulate MSI-X mask bits for assigned devices
On Tue, Sep 28, 2010 at 05:44:09PM +0800, Sheng Yang wrote: Hi Avi Marcelo This patchset would add emulation of MSI-X mask bit for assigned devices in QEmu. BTW: We are also purposed an acceleration of MSI-X mask bit for KVM - to get it done in kernel. That's because sometime MSI-X mask bit was accessed very frequently by guest and emulation in QEmu cost a lot(tens to hundreds percent CPU utilization sometime), e.g. guest using Linux 2.6.18 or under some heavy workload. The method has been proved efficient in Xen, but it would require VMM to handle MSI-X table. Is that OK with you? It would be good to understand where that cost is, before. Eg. do you commit kvm irq route frequently when guest unmasks? -- 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
[PATCH 0/3] Emulate MSI-X mask bits for assigned devices
Hi Avi Marcelo This patchset would add emulation of MSI-X mask bit for assigned devices in QEmu. BTW: We are also purposed an acceleration of MSI-X mask bit for KVM - to get it done in kernel. That's because sometime MSI-X mask bit was accessed very frequently by guest and emulation in QEmu cost a lot(tens to hundreds percent CPU utilization sometime), e.g. guest using Linux 2.6.18 or under some heavy workload. The method has been proved efficient in Xen, but it would require VMM to handle MSI-X table. Is that OK with you? -- regards Yang, Sheng -- 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
