From patchwork Thu Jan 5 17:13:40 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ian Campbell X-Patchwork-Id: 134520 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 0DB9C1007D6 for ; Fri, 6 Jan 2012 04:23:40 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932128Ab2AERXf (ORCPT ); Thu, 5 Jan 2012 12:23:35 -0500 Received: from smtp02.citrix.com ([66.165.176.63]:49271 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755401Ab2AERXe (ORCPT ); Thu, 5 Jan 2012 12:23:34 -0500 X-Greylist: delayed 583 seconds by postgrey-1.27 at vger.kernel.org; Thu, 05 Jan 2012 12:23:34 EST X-IronPort-AV: E=Sophos;i="4.71,462,1320642000"; d="scan'208";a="176424838" Received: from ftlpmailmx02.citrite.net ([10.13.107.66]) by FTLPIPO02.CITRIX.COM with ESMTP/TLS/RC4-MD5; 05 Jan 2012 12:13:49 -0500 Received: from smtp01.ad.xensource.com (10.219.128.104) by smtprelay.citrix.com (10.13.107.66) with Microsoft SMTP Server id 8.3.213.0; Thu, 5 Jan 2012 12:13:49 -0500 Received: from cosworth.uk.xensource.com (cosworth.uk.xensource.com [10.80.16.52]) by smtp01.ad.xensource.com (8.13.1/8.13.1) with ESMTP id q05HDjo5015239; Thu, 5 Jan 2012 09:13:47 -0800 From: Ian Campbell To: netdev@vger.kernel.org CC: David Miller , Eric Dumazet , Ian Campbell Subject: [PATCH 2/6] net: pad skb data and shinfo as a whole rather than individually Date: Thu, 5 Jan 2012 17:13:40 +0000 Message-ID: <1325783624-14601-2-git-send-email-ian.campbell@citrix.com> X-Mailer: git-send-email 1.7.2.5 In-Reply-To: <1325783399.25206.413.camel@zakaz.uk.xensource.com> References: <1325783399.25206.413.camel@zakaz.uk.xensource.com> MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org We already push the shinfo to the very end of the actual allocation which is already cache-line aligned. This reduces the minimum overhead required for this allocation such that the shinfo can be grown in the following patch without overflowing 2048 bytes for a 1500 byte frame. Reducing this overhead means that sometimes the tail end of the data can end up in the same cache line as the beginning of the shinfo but in many cases the allocation slop means that there is no overlap. Signed-off-by: Ian Campbell --- include/linux/skbuff.h | 4 ++-- net/core/skbuff.c | 3 +-- 2 files changed, 3 insertions(+), 4 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 50db9b0..f04333b 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -41,7 +41,7 @@ #define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \ ~(SMP_CACHE_BYTES - 1)) #define SKB_WITH_OVERHEAD(X) \ - ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info))) + ((X) - sizeof(struct skb_shared_info)) #define SKB_MAX_ORDER(X, ORDER) \ SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X)) #define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0)) @@ -50,7 +50,7 @@ /* return minimum truesize of one skb containing X bytes of data */ #define SKB_TRUESIZE(X) ((X) + \ SKB_DATA_ALIGN(sizeof(struct sk_buff)) + \ - SKB_DATA_ALIGN(sizeof(struct skb_shared_info))) + sizeof(struct skb_shared_info)) /* A. Checksumming of received packets by device. * diff --git a/net/core/skbuff.c b/net/core/skbuff.c index da0c97f..b6de604 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -189,8 +189,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask, * aligned memory blocks, unless SLUB/SLAB debug is enabled. * Both skb->head and skb_shared_info are cache line aligned. */ - size = SKB_DATA_ALIGN(size); - size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); + size = SKB_DATA_ALIGN(size + sizeof(struct skb_shared_info)); data = kmalloc_node_track_caller(size, gfp_mask, node); if (!data) goto nodata;