From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Liu Subject: Re: [PATCH net-next v2] xen-netback: Rework rx_work_todo Date: Mon, 20 Jan 2014 16:38:14 +0000 Message-ID: <20140120163814.GE11681@zion.uk.xensource.com> References: <1389805867-22409-1-git-send-email-zoltan.kiss@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: , , , , , To: Zoltan Kiss Return-path: Content-Disposition: inline In-Reply-To: <1389805867-22409-1-git-send-email-zoltan.kiss@citrix.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, Jan 15, 2014 at 05:11:07PM +0000, Zoltan Kiss wrote: > The recent patch to fix receive side flow control (11b57f) solved the spinning > thread problem, however caused an another one. The receive side can stall, if: > - [THREAD] xenvif_rx_action sets rx_queue_stopped to true > - [INTERRUPT] interrupt happens, and sets rx_event to true > - [THREAD] then xenvif_kthread sets rx_event to false > - [THREAD] rx_work_todo doesn't return true anymore > > Also, if interrupt sent but there is still no room in the ring, it take quite a > long time until xenvif_rx_action realize it. This patch ditch that two variable, > and rework rx_work_todo. If the thread finds it can't fit more skb's into the > ring, it saves the last slot estimation into rx_last_skb_slots, otherwise it's > kept as 0. Then rx_work_todo will check if: > - there is something to send to the ring (like before) > - there is space for the topmost packet in the queue > > I think that's more natural and optimal thing to test than two bool which are > set somewhere else. > > Signed-off-by: Zoltan Kiss Sorry for the delay. Paul, thanks for reviewing. Acked-by: Wei Liu Wei.