From: Paolo Bonzini <pbonzini@redhat.com>
To: Amit Shah <amit.shah@redhat.com>, Liang Li <liang.z.li@intel.com>
Cc: yang.z.zhang@intel.com, qemu-devel@nongnu.org,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
quintela@redhat.com
Subject: Re: [Qemu-devel] [PATCH 0/2] Optimization with AVX2 instruction
Date: Sun, 6 Sep 2015 16:43:46 +0200 [thread overview]
Message-ID: <55EC5122.4030802@redhat.com> (raw)
In-Reply-To: <20150902054009.GF13778@grmbl.mre>
On 02/09/2015 07:40, Amit Shah wrote:
>> The buffer_find_nonzero_offset() will be called to check the zero page
>> > during live migration, it's a hot function. buffer_find_nonzero_offset()
>> > has already been optimized with SSE2 instructions, for platform that
>> > supports AVX2, we can optimize this function with AVX2 instructions and
>> > achieve about 25% performance gain.
> This should be a good improvement. I recall Dave and I had a chat
> about this in the past too.
>
> I've not yet reviewed the patchset, but I doubt anyone will have
> objections. I'll review this shortly.
I think we need a better way to enable it than a configure option,
however. AVX2 machines are rare, and no one would end up using it
except perhaps Gentoo or other source-based distros.
Perhaps something like the GCC ifunc attribute?
Paolo
next prev parent reply other threads:[~2015-09-06 14:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-28 8:54 [Qemu-devel] [PATCH 0/2] Optimization with AVX2 instruction Liang Li
2015-08-28 8:54 ` [Qemu-devel] [PATCH 1/2] cutils: add the AVX2 optimization Liang Li
2015-08-28 8:54 ` [Qemu-devel] [PATCH 2/2] configure: add --enable-avx2 option Liang Li
2015-09-02 5:40 ` [Qemu-devel] [PATCH 0/2] Optimization with AVX2 instruction Amit Shah
2015-09-06 14:43 ` Paolo Bonzini [this message]
2015-09-08 6:16 ` Li, Liang Z
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