From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [RFC PATCH 2/2] ptr_ring_ll: pop/push multiple objects at once Date: Wed, 16 Nov 2016 07:23:25 +0200 Message-ID: <20161116072120-mutt-send-email-mst@kernel.org> References: <20161111043857.1547.70337.stgit@john-Precision-Tower-5810> <20161111044432.1547.65342.stgit@john-Precision-Tower-5810> <20161115010140-mutt-send-email-mst@kernel.org> <582BE39B.9050007@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: jasowang@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: John Fastabend Return-path: Content-Disposition: inline In-Reply-To: <582BE39B.9050007@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, Nov 15, 2016 at 08:42:03PM -0800, John Fastabend wrote: > On 16-11-14 03:06 PM, Michael S. Tsirkin wrote: > > On Thu, Nov 10, 2016 at 08:44:32PM -0800, John Fastabend wrote: > >> Signed-off-by: John Fastabend > > > > This will naturally reduce the cache line bounce > > costs, but so will a _many API for ptr-ring, > > doing lock-add many-unlock. > > > > the number of atomics also scales better with the lock: > > one per push instead of one per queue. > > > > Also, when can qdisc use a _many operation? > > > > On dequeue we can pull off many skbs instead of one at a time and > then either (a) pass them down as an array to the driver (I started > to write this on top of ixgbe and it seems like a win) or (b) pass > them one by one down to the driver and set the xmit_more bit correctly. > > The pass one by one also seems like a win because we avoid the lock > per skb. > > On enqueue qdisc side its a bit more evasive to start doing this. > > > [...] I see. So we could wrap __ptr_ring_consume and implement __skb_array_consume. You can call that in a loop under a lock. I would limit it to something small like 16 pointers, to make sure lock contention is not an issue. -- MST