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Re: [Qemu-devel] [PATCH 0/7] coroutine: optimizations


From: Peter Lieven
Subject: Re: [Qemu-devel] [PATCH 0/7] coroutine: optimizations
Date: Mon, 01 Dec 2014 08:05:17 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0

On 01.12.2014 06:55, Ming Lei wrote:
On Fri, Nov 28, 2014 at 10:12 PM, Paolo Bonzini <address@hidden> wrote:
As discussed in the other thread, this brings speedups from
dropping the coroutine mutex (which serializes multiple iothreads,
too) and using ELF thread-local storage.

The speedup in perf/cost is about 30% (190->145).  Windows port tested
with tests/test-coroutine.exe under Wine.
The data is very nice, and in my laptop, 'perf cost' can be decreased
from 244ns to 174ns.

BTW, the cost by using coroutine to run function isn't only from these
helpers(*_yield, *_enter, *_create, and perf-cost just measures
this part of cost), but also some implicit/invisible part. I have some
test cases which can show the problem. If someone is interested,
I can post them in list.

Of course, maybe the problem can be solved or impaired.

Peter



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