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
> 

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?

Thanks,
Jan


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