From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by dpdk.org (Postfix) with ESMTP id C1F045B40; Thu, 17 May 2018 04:04:07 +0200 (CEST) X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 May 2018 19:04:05 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.49,408,1520924400"; d="scan'208";a="39960082" Received: from debian.sh.intel.com (HELO debian) ([10.67.104.203]) by fmsmga007.fm.intel.com with ESMTP; 16 May 2018 19:04:04 -0700 Date: Thu, 17 May 2018 10:04:31 +0800 From: Tiwei Bie To: Maxime Coquelin Cc: dev@dpdk.org, mst@redhat.com, stable@dpdk.org Message-ID: <20180517020431.GA26242@debian> References: <20180516165423.5430-1-maxime.coquelin@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180516165423.5430-1-maxime.coquelin@redhat.com> User-Agent: Mutt/1.9.5 (2018-04-13) Subject: Re: [dpdk-dev] [PATCH v3] vhost: improve dirty pages logging performance X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 17 May 2018 02:04:08 -0000 On Wed, May 16, 2018 at 06:54:23PM +0200, 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 concurent accesses, Typo: concurent > 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 Apart from the typo, Reviewed-by: Tiwei Bie