[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization
From: |
Juan Quintela |
Subject: |
Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization |
Date: |
Thu, 12 Nov 2015 12:34:07 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
"Li, Liang Z" <address@hidden> wrote:
>> On 12/11/2015 10:40, Li, Liang Z wrote:
>> > I migrate a 8GB RAM Idle guest, I think most of it's pages are zero pages.
>> >
>> > I use your new code:
>> > -------------------------------------------------
>> > unsigned long *p = ...
>> > if (p[0] || p[1] || p[2] || p[3]
>> > || memcmp(p+4, p, size - 4 * sizeof(unsigned long)) != 0)
>> > return BUFFER_NOT_ZERO;
>> > else
>> > return BUFFER_ZERO;
>> > ---------------------------------------------------
>> > and the result is almost the same. I also tried the check 8, 16 long
>> > data at the beginning, same result.
>>
>> Interesting... Well, all I can say is that applaud you for testing
>> your hypothesis
>> with the benchmark.
>>
>> Probably the setup cost of memcmp is too high, because the testing loop is
>> already very optimized.
>>
>> Please submit the AVX2 version if it helps!
I read the email in the wrong order. Forget about my other email.
Sorry, Juan.
>
> Yes, the AVX2 version really helps. I have already submitted it, could
> you help to review it?
>
> I am curious about the original intention to add the SSE2 Intrinsics,
> is the same reason?
>
> I even suspect the VM may impact the 'memcmp()' performance, is it possible?
>
> Liang
>
>> Paolo
- Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization, (continued)
- Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization, Li, Liang Z, 2015/11/11
- Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization, Paolo Bonzini, 2015/11/12
- Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization, Li, Liang Z, 2015/11/12
- Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization, Paolo Bonzini, 2015/11/12
- Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization, Li, Liang Z, 2015/11/12
- Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization, Paolo Bonzini, 2015/11/12
- Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization, Li, Liang Z, 2015/11/12
- Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization,
Juan Quintela <=
- Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization, Li, Liang Z, 2015/11/12
- Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization, Dr. David Alan Gilbert, 2015/11/12
- Re: [Qemu-devel] [v2 0/2] add avx2 instruction optimization, Eric Blake, 2015/11/12