Re: [Qemu-devel] [PATCH v2 0/3] io-thread optimizations

[Aurelien Jarno <aurelien@aurel32.net>]

On Thu, Apr 14, 2011 at 09:14:35AM +0200, Jan Kiszka wrote:
> On 2011-04-13 22:16, Aurelien Jarno wrote:
> > On Mon, Apr 11, 2011 at 10:27:41PM +0200, Jan Kiszka wrote:
> >> These patches were posted before. They bring down the overhead of the
> >> io-thread mode for TCG here, specifically when emulating SMP.
> >>
> >> The major change in this version, besides rebasing, is the exclusion of
> >> KVM from the main loop polling optimization.
> >>
> >>
> >>
> >> Jan Kiszka (3):
> >>   Do not drop global mutex for polled main loop runs
> >>   Poll main loop after I/O events were received
> >>   Do not kick vcpus in TCG mode
> >>
> >>  cpus.c   |    2 +-
> >>  sysemu.h |    2 +-
> >>  vl.c     |   22 ++++++++++++++++------
> >>  3 files changed, 18 insertions(+), 8 deletions(-)
> >>
> > 
> > Thanks for working on improving the io-thread with TCG. Your patches 
> > make sense, but they don't seems to fix the slowdown observed when
> > enabling the io-thread. Well maybe they were not supposed to. This is
> > for example the results of netperf between guest and host using virtio:
> > 
> > no io-thread            122 MB/s
> > io-thread                97 MB/s
> > io-thread + patches      98 MB/s
> > 
> 
> Can you capture ftraces of io-thread enabled & disabled runs? They just
> need to cover a hand full of frames.
> 

>From what I have been able to get from the ftraces documentation, it's
possible multiple tracers. Which tracers would you like to use there?
The best would be a set of command lines to run.




-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net