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

[Jan Kiszka <jan.kiszka@web.de>]

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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.

Thanks,
Jan


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