Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755774Ab3EUTco (ORCPT ); Tue, 21 May 2013 15:32:44 -0400 Received: from git.silcnet.org ([81.89.56.81]:34928 "EHLO git.silcnet.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752054Ab3EUTcm (ORCPT ); Tue, 21 May 2013 15:32:42 -0400 Date: Tue, 21 May 2013 21:31:51 +0200 (CEST) From: Pekka Riikonen X-X-Sender: priikone@git.silcnet.org To: David Miller cc: eric.dumazet@gmail.com, eliezer.tamir@linux.intel.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, jesse.brandeburg@intel.com, donald.c.skidmore@intel.com, e1000-devel@lists.sourceforge.net, willemb@google.com, andi@firstfloor.org, hpa@zytor.com, eliezer@tamir.org.il Subject: Re: [PATCH v3 net-next 1/4] net: implement support for low latency socket polling In-Reply-To: <20130521.114921.460497085402760002.davem@davemloft.net> Message-ID: References: <519B2237.20204@linux.intel.com> <1369142926.3301.213.camel@edumazet-glaptop> <20130521.114921.460497085402760002.davem@davemloft.net> User-Agent: Alpine 2.00 (GSO 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1552 Lines: 42 On Tue, 21 May 2013, David Miller wrote: > From: Pekka Riikonen > Date: Tue, 21 May 2013 19:02:19 +0200 (CEST) > >> On Tue, 21 May 2013, Eric Dumazet wrote: >> >> : > > Alternatively, use a napi_id instead of a pointer. >> : > >> : > I'm not sure I understand what you propose. >> : >> : Oh well. >> : >> : To get a pointer to a struct net_device, we can use ifindex, and do a >> : rcu lookup into a hash table to get the net_device. We do not need >> : {pointer,ifindex} but {ifindex} is enough >> : >> : My suggestion is to not have skb->skb_ref but skb->napi_index : Its safe >> : to copy its value from skb->napi_index to sk->napi_index without >> : refcounting. >> : >> : All NAPI need to get a unique napi_index, and be inserted in a hash >> : table for immediate/fast lookup. >> : >> Maybe even that's not needed. Couldn't skb->queue_mapping give the >> correct NAPI instance in multiqueue nics? The NAPI instance could be made >> easily available from skb->dev. In any case an index is much better than >> a new pointer. > > Queue mapping is more volatile, and consider layered devices. > Yes, true. The napi_index then is probably the way to go. Main thing for me is that it doesn't increase skb size when in union with dma_cookie (skb has been growing lately). Pekka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/