From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by dpdk.org (Postfix) with ESMTP id 10F3B5F4D; Thu, 17 May 2018 14:01:58 +0200 (CEST) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9C95D4067F19; Thu, 17 May 2018 12:01:57 +0000 (UTC) Received: from [10.36.112.66] (ovpn-112-66.ams2.redhat.com [10.36.112.66]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2F2AB6B59B; Thu, 17 May 2018 12:01:53 +0000 (UTC) To: dev@dpdk.org, tiwei.bie@intel.com, mst@redhat.com Cc: stable@dpdk.org References: <20180517114447.28205-1-maxime.coquelin@redhat.com> From: Maxime Coquelin Message-ID: <81a73714-9a7f-0b64-d508-2eb03422fe06@redhat.com> Date: Thu, 17 May 2018 14:01:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180517114447.28205-1-maxime.coquelin@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Thu, 17 May 2018 12:01:57 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Thu, 17 May 2018 12:01:57 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'maxime.coquelin@redhat.com' RCPT:'' Subject: Re: [dpdk-stable] [PATCH v4] vhost: improve dirty pages logging performance X-BeenThere: stable@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches for DPDK stable branches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 17 May 2018 12:01:58 -0000 Hi Tiwei, On 05/17/2018 01:44 PM, Maxime Coquelin wrote: > This patch caches all dirty pages logging until the used ring index > is updated. > > The goal of this optimization is to fix a performance regression > introduced when the vhost library started to use atomic operations > to set bits in the shared dirty log map. While the fix was valid > as previous implementation wasn't safe against concurrent accesses, > contention was induced. > > With this patch, during migration, we have: > 1. Less atomic operations as only a single atomic OR operation > per 32 or 64 (depending on CPU) pages. > 2. Less atomic operations as during a burst, the same page will > be marked dirty only once. > 3. Less write memory barriers. > > Fixes: 897f13a1f726 ("vhost: make page logging atomic") > > Cc:stable@dpdk.org > > Cc: Tiwei Bie > Suggested-by: Michael S. Tsirkin > Signed-off-by: Maxime Coquelin I missed to add your: Reviewed-by: Tiwei Bie that you replied to v3, and since the changes in v4 were suggested by you, I guess it still applies. Cheers, Maxime