From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Emilio G. Cota" Subject: Re: [PATCH v3 2/5] util: introduce threaded workqueue Date: Fri, 23 Nov 2018 19:17:34 -0500 Message-ID: <20181124001734.GF17229@flamenco> References: <20181122072028.22819-1-xiaoguangrong@tencent.com> <20181122072028.22819-3-xiaoguangrong@tencent.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org, mst@redhat.com, mtosatti@redhat.com, Xiao Guangrong , dgilbert@redhat.com, peterx@redhat.com, qemu-devel@nongnu.org, quintela@redhat.com, wei.w.wang@intel.com, jiang.biao2@zte.com.cn, pbonzini@redhat.com To: guangrong.xiao@gmail.com Return-path: Content-Disposition: inline In-Reply-To: <20181122072028.22819-3-xiaoguangrong@tencent.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel2=m.gmane.org@nongnu.org Sender: "Qemu-devel" List-Id: kvm.vger.kernel.org On Thu, Nov 22, 2018 at 15:20:25 +0800, guangrong.xiao@gmail.com wrote: > +static uint64_t get_free_request_bitmap(Threads *threads, ThreadLocal *thread) > +{ > + uint64_t request_fill_bitmap, request_done_bitmap, result_bitmap; > + > + request_fill_bitmap = atomic_rcu_read(&thread->request_fill_bitmap); > + request_done_bitmap = atomic_rcu_read(&thread->request_done_bitmap); > + bitmap_xor(&result_bitmap, &request_fill_bitmap, &request_done_bitmap, > + threads->thread_requests_nr); This is not wrong, but it's a big ugly. Instead, I would: - Introduce bitmap_xor_atomic in a previous patch - Use bitmap_xor_atomic here, getting rid of the rcu reads Thanks, Emilio From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36960) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gQLdl-0001ua-Oq for qemu-devel@nongnu.org; Fri, 23 Nov 2018 19:17:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gQLdh-00066M-Bm for qemu-devel@nongnu.org; Fri, 23 Nov 2018 19:17:41 -0500 Received: from out4-smtp.messagingengine.com ([66.111.4.28]:39383) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gQLdh-0005zF-7h for qemu-devel@nongnu.org; Fri, 23 Nov 2018 19:17:37 -0500 Date: Fri, 23 Nov 2018 19:17:34 -0500 From: "Emilio G. Cota" Message-ID: <20181124001734.GF17229@flamenco> References: <20181122072028.22819-1-xiaoguangrong@tencent.com> <20181122072028.22819-3-xiaoguangrong@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181122072028.22819-3-xiaoguangrong@tencent.com> Subject: Re: [Qemu-devel] [PATCH v3 2/5] util: introduce threaded workqueue List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: guangrong.xiao@gmail.com Cc: pbonzini@redhat.com, mst@redhat.com, mtosatti@redhat.com, qemu-devel@nongnu.org, kvm@vger.kernel.org, dgilbert@redhat.com, peterx@redhat.com, wei.w.wang@intel.com, jiang.biao2@zte.com.cn, eblake@redhat.com, quintela@redhat.com, Xiao Guangrong On Thu, Nov 22, 2018 at 15:20:25 +0800, guangrong.xiao@gmail.com wrote: > +static uint64_t get_free_request_bitmap(Threads *threads, ThreadLocal *thread) > +{ > + uint64_t request_fill_bitmap, request_done_bitmap, result_bitmap; > + > + request_fill_bitmap = atomic_rcu_read(&thread->request_fill_bitmap); > + request_done_bitmap = atomic_rcu_read(&thread->request_done_bitmap); > + bitmap_xor(&result_bitmap, &request_fill_bitmap, &request_done_bitmap, > + threads->thread_requests_nr); This is not wrong, but it's a big ugly. Instead, I would: - Introduce bitmap_xor_atomic in a previous patch - Use bitmap_xor_atomic here, getting rid of the rcu reads Thanks, Emilio