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Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode |
Date: |
Thu, 31 Jul 2014 11:15:44 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 |
Il 31/07/2014 10:59, Ming Lei ha scritto:
>> > No guesses please. Actually that's also my guess, but since you are
>> > submitting the patch you must do better and show profiles where stack
>> > switching disappears after the patches.
> Follows the below hardware events reported by 'perf stat' when running
> fio randread benchmark for 2min in VM(single vq, 2 jobs):
>
> sudo ~/bin/perf stat -e
> L1-dcache-loads,L1-dcache-load-misses,cpu-cycles,instructions,branch-instructions,branch-misses,branch-loads,branch-load-misses,dTLB-loads,dTLB-load-misses
> ./nqemu-start-mq 4 1
>
> 1), without bypassing coroutine via forcing to set 's->raw_format ' as
> false, see patch 5/15
>
> - throughout: 95K
> 232,564,905,115 instructions
> 161.991075781 seconds time elapsed
>
>
> 2), with bypassing coroutinue
> - throughput: 115K
> 255,526,629,881 instructions
> 162.333465490 seconds time elapsed
Ok, so you are saving 10% instructions per iop: before 232G / 95K =
2.45M instructions/iop, 255G / 115K = 2.22M instructions/iop.
That's not small, and it's a good thing for CPU utilization even if you
were not increasing iops. On top of this, can you provide the stack
traces to see the difference in the profiles?
Paolo
- [Qemu-devel] [PATCH 00/14] dataplane: optimization and multi virtqueue support, Ming Lei, 2014/07/30
- [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, Ming Lei, 2014/07/30
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, Paolo Bonzini, 2014/07/30
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, Ming Lei, 2014/07/30
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, Paolo Bonzini, 2014/07/30
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, Ming Lei, 2014/07/30
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, BenoƮt Canet, 2014/07/31
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, Ming Lei, 2014/07/31
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, Paolo Bonzini, 2014/07/31
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, Ming Lei, 2014/07/31
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, Ming Lei, 2014/07/31
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, Ming Lei, 2014/07/31
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, Paolo Bonzini, 2014/07/31
- Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode, Ming Lei, 2014/07/31
[Qemu-devel] [PATCH 02/15] qemu aio: prepare for supporting selective bypass coroutine, Ming Lei, 2014/07/30
[Qemu-devel] [PATCH 03/15] block: support to bypass qemu coroutinue, Ming Lei, 2014/07/30
[Qemu-devel] [PATCH 04/15] Revert "raw-posix: drop raw_get_aio_fd() since it is no longer used", Ming Lei, 2014/07/30
[Qemu-devel] [PATCH 05/15] dataplane: enable selective bypassing coroutine, Ming Lei, 2014/07/30
[Qemu-devel] [PATCH 06/15] qemu/obj_pool.h: introduce object allocation pool, Ming Lei, 2014/07/30
[Qemu-devel] [PATCH 07/15] dataplane: use object pool to speed up allocation for virtio blk request, Ming Lei, 2014/07/30