From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Coquelin Subject: Re: [PATCH] vhost: avoid concurrency when logging dirty pages Date: Fri, 30 Mar 2018 09:42:39 +0200 Message-ID: References: <20180321154413.1120-1-maxime.coquelin@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: stable@dpdk.org To: dev@dpdk.org, jianfeng.tan@intel.com, tiwei.bie@intel.com, jfreimann@redhat.com Return-path: In-Reply-To: <20180321154413.1120-1-maxime.coquelin@redhat.com> Content-Language: en-US List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 03/21/2018 04:44 PM, Maxime Coquelin wrote: > This patch aims at fixing a migration performance regression > faced since atomic operation is used to log pages as dirty when > doing live migration. > > Instead of setting a single bit by doing an atomic read-modify-write > operation to log a page as dirty, this patch write 0xFF to the > corresponding byte, and so logs 8 page as dirty. > > The advantage is that it avoids concurrent atomic operations by > multiple PMD threads, the drawback is that some clean pages are > marked as dirty and so are transferred twice. > > Fixes: 897f13a1f726 ("vhost: make page logging atomic") > Cc: stable@dpdk.org > > Signed-off-by: Maxime Coquelin > --- > lib/librte_vhost/vhost.h | 12 ++++-------- > 1 file changed, 4 insertions(+), 8 deletions(-) Applied to dpdk-next-virtio/master.