From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36182) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bNNWw-00066Z-DC for qemu-devel@nongnu.org; Wed, 13 Jul 2016 13:01:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bNNWr-0005Ls-EK for qemu-devel@nongnu.org; Wed, 13 Jul 2016 13:01:02 -0400 Received: from mail-lf0-x236.google.com ([2a00:1450:4010:c07::236]:35732) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bNNWr-0005LN-5d for qemu-devel@nongnu.org; Wed, 13 Jul 2016 13:00:57 -0400 Received: by mail-lf0-x236.google.com with SMTP id f93so44044505lfi.2 for ; Wed, 13 Jul 2016 10:00:56 -0700 (PDT) References: <1468354426-837-1-git-send-email-sergey.fedorov@linaro.org> <148a0c48-f58c-6d95-8b97-6449670019ac@redhat.com> From: Sergey Fedorov Message-ID: <578673C5.3060108@gmail.com> Date: Wed, 13 Jul 2016 20:00:53 +0300 MIME-Version: 1.0 In-Reply-To: <148a0c48-f58c-6d95-8b97-6449670019ac@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 00/11] Reduce lock contention on TCG hot-path List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , =?UTF-8?Q?Alex_Benn=c3=a9e?= Cc: Sergey Fedorov , qemu-devel@nongnu.org, mttcg@listserver.greensocs.com, fred.konrad@greensocs.com, a.rigo@virtualopensystems.com, cota@braap.org, bobby.prani@gmail.com, rth@twiddle.net, peter.maydell@linaro.org, patches@linaro.org, claudio.fontana@huawei.com, mark.burton@greensocs.com, jan.kiszka@siemens.com On 13/07/16 10:39, Paolo Bonzini wrote: > On 12/07/2016 22:13, Sergey Fedorov wrote: >> From: Sergey Fedorov >> >> Hi, >> >> This is my respin of Alex's v2 series [1]. >> >> The first 8 patches are preparation for the patch 9, the subject matter >> of this series, which enables lockless translation block lookup. The >> main change here is that Paolo's suggestion is implemented: TBs are >> marked with invalid CPU state early during invalidation. This allows to >> make lockless lookup safe from races on 'tb_jmp_cache' and direct block >> chaining. > Thanks for looking at the suggestion again and especially for perfecting it! > >> The patch 10 is a simple solution to avoid unnecessary bouncing on >> 'tb_lock' between tb_gen_code() and tb_add_jump(). A local variable is >> used to keep track of whether 'tb_lock' has already been taken. >> >> The last patch is my attempt to restructure tb_find_{fast,slow}() into a >> single function tb_find(). I think it will be easier to follow the >> locking scheme this way. However, I am afraid this last patch can be >> controversial, so it can be simply dropped. > Actually I agree entirely with it. > > If anything, for historical reasons one might rename tb_find_physical to > tb_find_slow and leave the tb_find_fast name, but I think the patch is > good as is. Nice to hear that :) > > Have you measured performance with the series? In any case, it's nice > to see MTTCG finally taking shape! No, I didn't measured the performance. Maybe Alex can help me with this? Thanks, Sergey