From patchwork Tue Jan 18 15:24:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Abeni X-Patchwork-Id: 12716648 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3EF46C433F5 for ; Tue, 18 Jan 2022 15:25:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344683AbiARPZU (ORCPT ); Tue, 18 Jan 2022 10:25:20 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:39552 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242695AbiARPZR (ORCPT ); Tue, 18 Jan 2022 10:25:17 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1642519516; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=V6TEMHfkJFFsNPCEXQEWk8iYL0SnF/mJ5afISlqyFkk=; b=Fb1QNyEAnwQ+0r35eZDETRWDWDYykgjt4sBYhd80xVRCt3N90mjgjcSzh4aiGi5SGvadJU 984Ctyr2DOCYLEQiDGlnlP4HPz8Ven6W18kWlHIFexN8376xCPm0zpwd7T9HZMf3dESPn0 9W7pK7NoAurrBJr43ku8jpEmePlOZFE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-592-Fhdy4-gtM8GE1lMHhBEhVg-1; Tue, 18 Jan 2022 10:25:15 -0500 X-MC-Unique: Fhdy4-gtM8GE1lMHhBEhVg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0A43B1018725; Tue, 18 Jan 2022 15:25:14 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.39.194.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4227D106C063; Tue, 18 Jan 2022 15:25:13 +0000 (UTC) From: Paolo Abeni To: netdev@vger.kernel.org Cc: Eric Dumazet Subject: [RFC PATCH 2/3] net: gro: minor optimization for dev_gro_receive() Date: Tue, 18 Jan 2022 16:24:19 +0100 Message-Id: <35d722e246b7c4afb6afb03760df6f664db4ef05.1642519257.git.pabeni@redhat.com> In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org X-Patchwork-State: RFC While inspecting some perf report, I noticed that the compiler emits suboptimal code for the napi CB initialization, fetching and storing multiple times the memory for flags bitfield. This is with gcc 10.3.1, but I observed the same with older compiler versions. We can help the compiler to do a nicer work e.g. initially setting all the bitfield to 0 using an u16 alias. The generated code is quite smaller, with the same number of conditional Before: objdump -t net/core/gro.o | grep " F .text" 0000000000000bb0 l F .text 0000000000000357 dev_gro_receive After: 0000000000000bb0 l F .text 000000000000033c dev_gro_receive Signed-off-by: Paolo Abeni --- include/net/gro.h | 13 +++++++++---- net/core/gro.c | 16 +++++----------- 2 files changed, 14 insertions(+), 15 deletions(-) diff --git a/include/net/gro.h b/include/net/gro.h index 8f75802d50fd..a068b27d341f 100644 --- a/include/net/gro.h +++ b/include/net/gro.h @@ -29,14 +29,17 @@ struct napi_gro_cb { /* Number of segments aggregated. */ u16 count; - /* Start offset for remote checksum offload */ - u16 gro_remcsum_start; + /* Used in ipv6_gro_receive() and foo-over-udp */ + u16 proto; /* jiffies when first packet was created/queued */ unsigned long age; - /* Used in ipv6_gro_receive() and foo-over-udp */ - u16 proto; + /* portion of the cb set to zero at every gro iteration */ + u32 zeroed_start[0]; + + /* Start offset for remote checksum offload */ + u16 gro_remcsum_start; /* This is non-zero if the packet may be of the same flow. */ u8 same_flow:1; @@ -70,6 +73,8 @@ struct napi_gro_cb { /* GRO is done by frag_list pointer chaining. */ u8 is_flist:1; + u32 zeroed_end[0]; + /* used to support CHECKSUM_COMPLETE for tunneling protocols */ __wsum csum; diff --git a/net/core/gro.c b/net/core/gro.c index d43d42215bdb..b9ebe9298731 100644 --- a/net/core/gro.c +++ b/net/core/gro.c @@ -435,6 +435,9 @@ static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head) napi_gro_complete(napi, oldest); } +#define zeroed_len (offsetof(struct napi_gro_cb, zeroed_end) - \ + offsetof(struct napi_gro_cb, zeroed_start)) + static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb) { u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1); @@ -459,29 +462,20 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff skb_set_network_header(skb, skb_gro_offset(skb)); skb_reset_mac_len(skb); - NAPI_GRO_CB(skb)->same_flow = 0; + BUILD_BUG_ON(zeroed_len != sizeof(NAPI_GRO_CB(skb)->zeroed_start[0])); + NAPI_GRO_CB(skb)->zeroed_start[0] = 0; NAPI_GRO_CB(skb)->flush = skb_is_gso(skb) || skb_has_frag_list(skb); - NAPI_GRO_CB(skb)->free = 0; - NAPI_GRO_CB(skb)->encap_mark = 0; - NAPI_GRO_CB(skb)->recursion_counter = 0; - NAPI_GRO_CB(skb)->is_fou = 0; NAPI_GRO_CB(skb)->is_atomic = 1; - NAPI_GRO_CB(skb)->gro_remcsum_start = 0; /* Setup for GRO checksum validation */ switch (skb->ip_summed) { case CHECKSUM_COMPLETE: NAPI_GRO_CB(skb)->csum = skb->csum; NAPI_GRO_CB(skb)->csum_valid = 1; - NAPI_GRO_CB(skb)->csum_cnt = 0; break; case CHECKSUM_UNNECESSARY: NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1; - NAPI_GRO_CB(skb)->csum_valid = 0; break; - default: - NAPI_GRO_CB(skb)->csum_cnt = 0; - NAPI_GRO_CB(skb)->csum_valid = 0; } pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,