On 2011-04-11 22:18, Jan Kiszka wrote: > 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. In fact, they were already prepared. So I've just sent them out. Jan
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