From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tiwei Bie Subject: Re: [PATCH v3] vhost: improve dirty pages logging performance Date: Thu, 17 May 2018 10:04:31 +0800 Message-ID: <20180517020431.GA26242@debian> References: <20180516165423.5430-1-maxime.coquelin@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: dev@dpdk.org, mst@redhat.com, stable@dpdk.org To: Maxime Coquelin Return-path: Content-Disposition: inline In-Reply-To: <20180516165423.5430-1-maxime.coquelin@redhat.com> 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 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