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Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virt
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support |
Date: |
Wed, 06 Aug 2014 10:50:53 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 |
Il 06/08/2014 10:38, Ming Lei ha scritto:
> On Wed, Aug 6, 2014 at 3:45 PM, Paolo Bonzini <address@hidden> wrote:
>> Il 06/08/2014 07:33, Ming Lei ha scritto:
>>>>> I played a bit with the following, I hope it's not too naive. I couldn't
>>>>> see a difference with your patches, but at least one reason for this is
>>>>> probably that my laptop SSD isn't fast enough to make the CPU the
>>>>> bottleneck. Haven't tried ramdisk yet, that would probably be the next
>>>>> thing. (I actually wrote the patch up just for some profiling on my own,
>>>>> not for comparing throughput, but it should be usable for that as well.)
>>> This might not be good for the test since it is basically a sequential
>>> read test, which can be optimized a lot by kernel. And I always use
>>> randread benchmark.
>>
>> A microbenchmark already exists in tests/test-coroutine.c, and doesn't
>> really tell us much; it's obvious that coroutines execute more code, the
>> question is why it affects the iops performance.
>
> Could you take a look at the coroutine benchmark I worte? The running
> result shows coroutine does decrease performance a lot compared with
> bypass coroutine like the patchset is doing.
Your benchmark is synchronous, while disk I/O is asynchronous.
Your benchmark doesn't add much compared to "time tests/test-coroutine
-m perf -p /perf/yield". It takes 8 seconds on my machine, and 10^8
function calls obviously take less than 8 seconds. I've sent a patch to
add a "baseline" function call benchmark to test-coroutine.
>> The sequential read should be the right workload. For fio, you want to
>> get as many iops as possible to QEMU and so you need randread. But
>> qemu-img is not run in a guest and if the kernel optimizes sequential
>> reads then the bypass should have even more benefits because it makes
>> userspace proportionally more expensive.
Do you agree with this?
Paolo
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, (continued)
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Kevin Wolf, 2014/08/05
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Ming Lei, 2014/08/05
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Paolo Bonzini, 2014/08/05
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Stefan Hajnoczi, 2014/08/05
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Kevin Wolf, 2014/08/05
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Ming Lei, 2014/08/06
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Paolo Bonzini, 2014/08/06
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Ming Lei, 2014/08/06
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Ming Lei, 2014/08/06
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Kevin Wolf, 2014/08/06
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Ming Lei, 2014/08/06
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Kevin Wolf, 2014/08/06
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Ming Lei, 2014/08/06
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Ming Lei, 2014/08/06
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Kevin Wolf, 2014/08/06
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Ming Lei, 2014/08/07
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Ming Lei, 2014/08/07
- Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support, Kevin Wolf, 2014/08/07