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

[Jan Kiszka]

On 2011-06-26 00:44, Andreas Färber wrote:
> Am 25.06.2011 um 10:38 schrieb Jan Kiszka:
> 
>> 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
>>>
>>
>> Given that everyone seems to agree that these patches are a step into
>> the right direction (for the current TCG locking architecture at least),
>> can we please finally apply them? They do have positive impact in some
>> use cases. If rebasing is required (I don't think so), just let me know.
>>
>> BTW, did you make any progress with tracing the remaining issues?
> 
> I've tested these together with Paolo's fixes, but it still hangs on
> Darwin. Doesn't appear to make it worse though.

http://thread.gmane.org/gmane.comp.emulators.qemu/106225 is still not
merged.

Jan

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