From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51167) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aXkAt-0000Xk-9B for qemu-devel@nongnu.org; Mon, 22 Feb 2016 01:40:52 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aXkAp-0008BK-N6 for qemu-devel@nongnu.org; Mon, 22 Feb 2016 01:40:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45241) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aXkAp-0008B0-HR for qemu-devel@nongnu.org; Mon, 22 Feb 2016 01:40:47 -0500 Date: Mon, 22 Feb 2016 12:10:39 +0530 From: Amit Shah Message-ID: <20160222064039.GB10967@grmbl.mre> References: <1453880034-25076-1-git-send-email-liang.z.li@intel.com> <56A8D235.8040705@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH v5 0/2] add avx2 instruction optimization List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Li, Liang Z" Cc: "peter.maydell@linaro.org" , "quintela@redhat.com" , "qemu-devel@nongnu.org" , "dgilbert@redhat.com" , "stefanha@redhat.com" , Paolo Bonzini , "rth@twiddle.net" On (Mon) 22 Feb 2016 [06:23:54], Li, Liang Z wrote: > > On 27/01/2016 08:33, Liang Li wrote: > > > buffer_find_nonzero_offset() is a hot function during live migration. > > > Now it use SSE2 instructions for optimization. For platform supports > > > AVX2 instructions, use the AVX2 instructions for optimization can help > > > to improve the performance of zero page checking about 30% comparing > > > to SSE2. > > > Live migration can be faster with this optimization, the test result > > > shows that for an 8GB RAM idle guest, this patch can help to shorten > > > the total live migration time about 6%. > > > > > > This patch use the ifunc mechanism to select the proper function when > > > running, for platform supports AVX2, execute the AVX2 instructions, > > > else, execute the original instructions. > > > > > > With this patch, the QEMU binary can run on both platforms support > > > AVX2 or not. > > > > > > Compiler which doesn't support the AVX2 and ifunc attribute can also > > > build the source code successfully. > > > > > > v5 -> v4 changes: > > > * Enhance the ifunc attribute detection (Paolo's suggestion) > > > > > > v3 -> v4 changes: > > > * Use the GCC #pragma to make things simple (Paolo's suggestion) > > > * Put avx2 related code in cutils.c (Richard's suggestion) > > > * Change the configure, detect ifunc and avx2 attributes together > > > > > > v2 -> v3 changes: > > > * Detect the ifunc attribute support (Paolo's suggestion) > > > * Use the ifunc attribute instead of the inline asm (Richard's suggestion) > > > * Change the configure (Juan's suggestion) > > > > > > Liang Li (2): > > > configure: detect ifunc and avx2 attribute > > > cutils: add avx2 instruction optimization > > > > > > configure | 21 +++++++++ > > > include/qemu-common.h | 8 +--- > > > util/cutils.c | 118 > > ++++++++++++++++++++++++++++++++++++++++++++++++-- > > > 3 files changed, 136 insertions(+), 11 deletions(-) > > > > Reviewed-by: Paolo Bonzini > > This patch set is pending here for a long time, who can help to make it merged? Not sure; I could take it from the migration tree if no one objects. Amit