From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43988) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bLF8K-0002bM-ID for qemu-devel@nongnu.org; Thu, 07 Jul 2016 15:38:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bLF8F-0006xx-EF for qemu-devel@nongnu.org; Thu, 07 Jul 2016 15:38:47 -0400 Received: from mail-wm0-x22f.google.com ([2a00:1450:400c:c09::22f]:37701) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bLF8E-0006xb-4m for qemu-devel@nongnu.org; Thu, 07 Jul 2016 15:38:43 -0400 Received: by mail-wm0-x22f.google.com with SMTP id k123so3421525wme.0 for ; Thu, 07 Jul 2016 12:38:42 -0700 (PDT) References: <1467735496-16256-1-git-send-email-alex.bennee@linaro.org> <20160707160439.GA28053@flamenco> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: <20160707160439.GA28053@flamenco> Date: Thu, 07 Jul 2016 20:38:43 +0100 Message-ID: <8760shme64.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH v2 0/6] Reduce lock contention on TCG hot-path List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Emilio G. Cota" Cc: mttcg@listserver.greensocs.com, qemu-devel@nongnu.org, fred.konrad@greensocs.com, a.rigo@virtualopensystems.com, serge.fdrv@gmail.com, bobby.prani@gmail.com, rth@twiddle.net, mark.burton@greensocs.com, pbonzini@redhat.com, jan.kiszka@siemens.com, peter.maydell@linaro.org, claudio.fontana@huawei.com Emilio G. Cota writes: > On Tue, Jul 05, 2016 at 17:18:10 +0100, Alex Bennée wrote: >> Well this is the first re-spin of the series posted last week. I've >> added a bunch of additional patches to be more aggressive with >> avoiding bouncing locks but to be honest the numbers don't seem to >> make it worth it. > > How many threads are you using? With just a few threads I wouldn't > expect a measurable difference. My setup is 8 "cores" which pigz expands to use but I know you have beefier machines on hand ;-) > >> I think the first 3 patches are ready to take if the TCG maintainers >> want to: >> >> tcg: Ensure safe tb_jmp_cache lookup out of 'tb_lock' >> tcg: set up tb->page_addr before insertion >> tcg: cpu-exec: remove tb_lock from the hot-path > > I think it would be simpler to use tb_lock_recursive and > tb_lock_reset, as pointed out in v1 of this series. I didn't realise people were suggesting asymmetric lock taking/reseting. It seems ugly IMHO. > > Thanks, > > Emilio -- Alex Bennée