From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C57CFC0044C for ; Thu, 8 Nov 2018 01:46:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CEB52086C for ; Thu, 8 Nov 2018 01:46:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="fkx1rbZw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7CEB52086C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728500AbeKHLTW (ORCPT ); Thu, 8 Nov 2018 06:19:22 -0500 Received: from mail-io1-f68.google.com ([209.85.166.68]:35164 "EHLO mail-io1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728376AbeKHLTW (ORCPT ); Thu, 8 Nov 2018 06:19:22 -0500 Received: by mail-io1-f68.google.com with SMTP id 79-v6so13473897iou.2; Wed, 07 Nov 2018 17:46:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=csWGnVVVFpNbuE1SB1MGKj094gsKUpU0jLP+zy5p7zw=; b=fkx1rbZweWll96uCB6mGGxOqdVUG5AtfnoE/wsCP5HokL7wd8ExT/SruncBPXNwfit 8ZpDNEBP4aDFXqML5ID32AFAPfUqeUXmLcmj3dFM6Z+y2TJZWU+c2JkLOyFI02wzgcdB akatjC5JXBxtH95dqYWxRnx5APb+G1xmxm1sP6Uy8dCtKxxu2rdHBQjUNmZ2iEx6B/SF auCezzzqx6mhw0Bxop1ntQkgvE9RRKoiDsi8jg/93xg1ieV1UU5wr+vD63rRxeDQCGff Jh43Eig43oNbokrJUtw9T2Etip/AWLaJKRdtnfTDku6MS65AIAU7/PeKrWcYaXfB0nIm W6Ng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=csWGnVVVFpNbuE1SB1MGKj094gsKUpU0jLP+zy5p7zw=; b=Ejz3AJf2C8QxH0WUlI5kMTJbvZqgoyKStcSPJoA3Njrmoj8amQ9+ql9aMmAmoroVB5 oLUwn7U/tR+5rFfOAs6nGIlLuT8tcN6xujhFxXUlJghDAe+QxYtBT97NVkzOiXJbBzdE ElI1zX1FCZ9wYrtUVeDcHldT+Z49O+93EFHPRp/54PgqcxGOcK3Z2bUVdLL01b+af21J qdn7xA6ONDr/BMD4IhEfnhlduq6vR+/+aIVdNCpiDcWVgkzYFrf0BOpesSE7BDBhRvy0 d+iSY8kuq9Cnfmma+uCMKMhgEkJVcIRufi4UB7Y4mvqaDNm+yz9/On6NF8OIMsVMGKdH v2cQ== X-Gm-Message-State: AGRZ1gJ0q8VUF9nFDKdAQBgFe5X87w6vozD3zONSy5bbsFQNjmLYp44q 4nbe4G6O/WHJPYWrPLZt0/sHN/5O701ZyUIE5do= X-Google-Smtp-Source: AJdET5fDyjyz1jsW1ys9dqzlrKUskYywIWHr1UwTOsBts5epKA+6TlZt4PPv389d56vHw8jsRy4sHxS+MhdlcRSvf1Q= X-Received: by 2002:a6b:9046:: with SMTP id s67-v6mr2064167iod.295.1541641578473; Wed, 07 Nov 2018 17:46:18 -0800 (PST) MIME-Version: 1.0 References: <1541589617-1607-1-git-send-email-laoar.shao@gmail.com> <1541589617-1607-2-git-send-email-laoar.shao@gmail.com> <560b2828-cb1b-5ab5-f98b-b042a7e483f8@gmail.com> In-Reply-To: <560b2828-cb1b-5ab5-f98b-b042a7e483f8@gmail.com> From: Yafang Shao Date: Thu, 8 Nov 2018 09:45:42 +0800 Message-ID: Subject: Re: [PATCH net-next] tcp: minor optimization in tcp ack fast path processing To: Eric Dumazet Cc: David Miller , Eric Dumazet , netdev , LKML , Joe Perches Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 7, 2018 at 11:16 PM Eric Dumazet wrote: > > > > On 11/07/2018 03:20 AM, Yafang Shao wrote: > > Bitwise operation is a little faster. > > > > So I replace after() with (flag & FLAG_SND_UNA_ADVANCED) as this flag is > > already set before. > > > > Cc: Joe Perches > > Signed-off-by: Yafang Shao > > --- > > net/ipv4/tcp_input.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c > > index 2868ef2..0167015 100644 > > --- a/net/ipv4/tcp_input.c > > +++ b/net/ipv4/tcp_input.c > > @@ -3610,7 +3610,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) > > if (flag & FLAG_UPDATE_TS_RECENT) > > tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq); > > > > - if (!(flag & FLAG_SLOWPATH) && after(ack, prior_snd_una)) { > > + if (!(flag & FLAG_SLOWPATH) && (flag & FLAG_SND_UNA_ADVANCED)) { > > /* Window is constant, pure forward advance. > > * No more checks are required. > > * Note, we use the fact that SND.UNA>=SND.WL2. > > > > What about reducing this to a single conditional jump ? > > if ((flag & (FLAG_SLOWPATH | FLAG_SND_UNA_ADVANCED)) == FLAG_SND_UNA_ADVANCED) { > That's better. Will change it. Thanks Yafang