On 2011-04-11 22:14, Alex Williamson wrote: > On Mon, 2011-04-11 at 22:04 +0200, Jan Kiszka wrote: >> On 2011-04-11 21:15, Luiz Capitulino wrote: >>> On Mon, 11 Apr 2011 13:00:32 -0600 >>> Alex Williamson <alex.williamson@xxxxxxxxxx> wrote: >>> >>>> On Mon, 2011-04-11 at 15:35 -0300, Luiz Capitulino wrote: >>>>> On Fri, 08 Apr 2011 19:50:57 -0500 >>>>> Anthony Liguori <anthony@xxxxxxxxxxxxx> wrote: >>>>> >>>>>> On 04/08/2011 06:25 PM, Luiz Capitulino wrote: >>>>>>> Hi there, >>>>>>> >>>>>>> Summary: >>>>>>> >>>>>>> - PXE boot in qemu.git (HEAD f124a41) is quite slow, more than 5 minutes. Got >>>>>>> the problem with e1000, virtio and rtl8139. However, pcnet *works* (it's >>>>>>> as fast as qemu-kvm.git) >>>>>>> >>>>>>> - PXE boot in qemu-kvm.git (HEAD df85c051) is fast, less than a minute. Tried >>>>>>> with e1000, virtio and rtl8139 (I don't remember if I tried with pcnet) >>>>>>> >>>> >>>> I was having this problem too, but I think it's because I forgot to >>>> build qemu with --enable-io-thread, which is the default for qemu-kvm. >>>> Can you re-configure and build with that and see if it's fast? Thanks, >>> >>> Yes, nice catch, it's faster with I/O thread enabled, even seem faster >>> than qemu-kvm.git. >> >> What's the performance under qemu-kvm with -no-kvm-irqchip? >> >>> >>> So, does this have to be fixed w/o I/O thread? >> >> If it's most probably an architectural deficit of non-io-thread mode, I >> would say let it rest in peace. But maybe it points to a generic issues >> that is just magnified by non-threaded mode. > > I've probably been told, but forget. Why isn't io-thread enabled by > default? Thanks, TCG performance still sucks in io-threaded mode. I've three patches in my queue that reduces the overhead a bit further - for me to a reasonable level (will post them the next days). But, still, YMMV depending on the workload. At least Windows should no longer we a functional blocker thanks to Paolo's work. Jan
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