From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id E7E31569A for ; Wed, 9 Dec 2015 09:40:27 +0100 (CET) Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga103.jf.intel.com with ESMTP; 09 Dec 2015 00:40:26 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,402,1444719600"; d="scan'208";a="10087607" Received: from yliu-dev.sh.intel.com (HELO yliu-dev) ([10.239.66.49]) by fmsmga004.fm.intel.com with ESMTP; 09 Dec 2015 00:40:26 -0800 Date: Wed, 9 Dec 2015 16:41:36 +0800 From: Yuanhan Liu To: "Xie, Huawei" Message-ID: <20151209084136.GN29571@yliu-dev.sh.intel.com> References: <1449027793-30975-1-git-send-email-yuanhan.liu@linux.intel.com> <1449027793-30975-3-git-send-email-yuanhan.liu@linux.intel.com> <20151202153050-mutt-send-email-victork@redhat.com> <20151209034251.GM29571@yliu-dev.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Cc: "dev@dpdk.org" , Victor Kaplansky , "Michael S. Tsirkin" Subject: Re: [dpdk-dev] [PATCH 2/4] vhost: introduce vhost_log_write X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 Dec 2015 08:40:28 -0000 On Wed, Dec 09, 2015 at 05:44:11AM +0000, Xie, Huawei wrote: > On 12/9/2015 11:41 AM, Yuanhan Liu wrote: > > On Wed, Dec 09, 2015 at 03:33:16AM +0000, Xie, Huawei wrote: > > ... > >>>> +static inline void __attribute__((always_inline)) > >>>> +vhost_log_write(struct virtio_net *dev, struct vhost_virtqueue *vq, > >>>> + uint64_t offset, uint64_t len) > >>>> +{ > >>>> + uint64_t addr = vq->log_guest_addr; > >>>> + uint64_t page; > >>>> + > >>>> + if (unlikely(((dev->features & (1ULL << VHOST_F_LOG_ALL)) == 0) || > >>>> + !dev->log_base || !len)) > >>>> + return; > >>> Isn't "likely" more appropriate in above, since the whole > >>> expression is expected to be true most of the time? > >> Victor: > >> So we are not always logging, what is the message that tells the backend > >> the migration is started? > > When log starts, VHOST_USER_SET_FEATURES request will be sent again, > > with VHOST_F_LOG_ALL feature bit set. > As the VHOST_USER_SET_FEATURES handling and rx/tx runs asynchronously, > we have to make sure we don't miss logging anything when this feature is > set. That's a good remind. Thanks. > For example, I doubt like in virtio_dev_rx, is the dev->features > volatile? No, it is not volatile. --yliu