On Wed, May 13, 2009 at 08:15:29AM -0600, Alex Williamson wrote: > On Wed, 2009-05-13 at 16:55 +0300, Michael S. Tsirkin wrote: > > On Wed, May 13, 2009 at 07:11:16AM -0600, Alex Williamson wrote: > > > On Wed, 2009-05-13 at 16:00 +0300, Avi Kivity wrote: > > > > Alex Williamson wrote: > > > > >> > > > > >> When you say "multiple times", it is several, or a lot more? > > > > >> > > > > >> Maybe it is NAPI? > > > > >> > > > > > > > > > > The system would run out of the ~1000 available GSIs in a minute or two > > > > > with just an e1000e available to the guest. So that's something on the > > > > > order of 10/s. This also causes a printk in the host ever time the > > > > > interrupt in enabled, which can't help performance and gets pretty > > > > > annoying for syslog. I was guessing some kind of interrupt mitigation, > > > > > such as NAPI, but a qlogic FC card seems to do it too (seemingly at a > > > > > slower rate). > > > > > > > > > > > > > I see. And what is the path by which it is disabled? The mask bit in > > > > the MSI entry? > > > > > > Yes, I believe the only path is via a write to the MSI capability in the > > > PCI config space. > > > > > > Alex > > > > Very surprising: I haven't seen any driver disable MSI expect on device > > destructor path. Is this a linux guest? > > Yes, Debian 2.6.26 kernel. I'll check it it behaves the same on newer > upstream kernels and try to figure out why it's doing it. > > Alex Maybe power management powers down the card? Why would that be? Or maybe it detects some error in emulation and resets the card? -- MST -- 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
