From mboxrd@z Thu Jan 1 00:00:00 1970 From: P@draigBrady.com Subject: Re: RFC: NAPI packet weighting patch Date: Thu, 23 Jun 2005 09:56:30 +0100 Message-ID: <42BA793E.4080008@draigBrady.com> References: <42A5284C.3060808@osdl.org> <1118147904.6320.108.camel@localhost.localdomain> <20050621.133704.08321534.davem@davemloft.net> <42B92490.40005@draigBrady.com> <1119469066.6918.168.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Cc: "David S. Miller" , gandalf@wlug.westbo.se, shemminger@osdl.org, mitch.a.williams@intel.com, john.ronciak@intel.com, mchan@broadcom.com, buytenh@wantstofly.org, jdmason@us.ibm.com, netdev@oss.sgi.com, Robert.Olsson@data.slu.se, ganesh.venkatesan@intel.com, jesse.brandeburg@intel.com Return-path: To: hadi@cyberus.ca In-Reply-To: <1119469066.6918.168.camel@localhost.localdomain> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org jamal wrote: > On Wed, 2005-22-06 at 09:42 +0100, P@draigBrady.com wrote: >=20 >=20 >>Yes the copy is essentially free here as the data is already cached. >> >>As a data point, I went the whole hog and used buffer recycling >>in my essentially packet sniffing application. I.E. there are no >>allocs per packet at all, and this make a HUGE difference. On a >>2x3.4GHz 2xe1000 system I can receive 620Kpps per port sustained >>into my userspace app which does a LOT of processing per packet. >>Without the buffer recycling is was around 250Kpps. >>Note I don't reuse an skb until the packet is copied into a >>PACKET_MMAP buffer. >=20 >=20 > Was this machine SMP? Yes. 2 x 3.4GHz P4s 1 logical CPU per port (irq affinity) 1 thread (NB on same logical CPU as irq (sched_affinity)) to do user space per packet processing. > NAPI involved? Yep. > I take it nothing interfering in > the middle with the headers? It uses the standard path to PACKET_MMAP buffer e1000_clean_rx_irq -> netif_receive_skb -> tpacket_rcv P=E1draig.