From: Thomas Monjalon <thomas.monjalon-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>
To: "Xie, Huawei" <huawei.xie-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: dev-VfR2kkLFssw@public.gmane.org,
Hayato Momma <h-momma-JhyGz2TFV9J8UrSeD/g0lQ@public.gmane.org>
Subject: Re: [memnic PATCH v2 6/7] pmd: add branch hint in recv/xmit
Date: Tue, 30 Sep 2014 16:51:10 +0200 [thread overview]
Message-ID: <5360316.uoHmy6EYU1@xps13> (raw)
In-Reply-To: <C37D651A908B024F974696C65296B57B0F2B03A9-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2014-09-30 14:38, Xie, Huawei:
> > - if (++next >= MEMNIC_NR_PACKET)
> > + if (unlikely(++next >= MEMNIC_NR_PACKET))
>
> On IA, compiler can use add, cmp and cmov to avoid branch.
> But If MEMNIC_NR_PACKET is always power of 2,
> it is better just next = (next + 1) & (MEMNIC_NR_PACKET - 1)
Power of 2 is not enforced for MEMNIC_NR_PACKET.
--
Thomas
prev parent reply other threads:[~2014-09-30 14:51 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-30 11:14 [memnic PATCH v2 6/7] pmd: add branch hint in recv/xmit Hiroshi Shimamoto
[not found] ` <7F861DC0615E0C47A872E6F3C5FCDDBD02AE26C5-ZmjkEB1lVlLt6d3pZDjeaEtBU8KWyXPq@public.gmane.org>
2014-09-30 13:39 ` Xie, Huawei
[not found] ` <C37D651A908B024F974696C65296B57B0F2B02B3-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2014-10-01 0:01 ` Hiroshi Shimamoto
[not found] ` <7F861DC0615E0C47A872E6F3C5FCDDBD02AE2DB5-ZmjkEB1lVlLt6d3pZDjeaEtBU8KWyXPq@public.gmane.org>
2014-10-01 6:12 ` Thomas Monjalon
2014-09-30 14:32 ` Neil Horman
[not found] ` <20140930143242.GI2193-B26myB8xz7F8NnZeBjwnZQMhkBWG/bsMQH7oEaQurus@public.gmane.org>
2014-09-30 23:52 ` Hiroshi Shimamoto
[not found] ` <7F861DC0615E0C47A872E6F3C5FCDDBD02AE2D37-ZmjkEB1lVlLt6d3pZDjeaEtBU8KWyXPq@public.gmane.org>
2014-10-01 8:44 ` Bruce Richardson
2014-10-01 9:12 ` Hiroshi Shimamoto
[not found] ` <7F861DC0615E0C47A872E6F3C5FCDDBD02AE3BAF-ZmjkEB1lVlLt6d3pZDjeaEtBU8KWyXPq@public.gmane.org>
2014-10-01 11:13 ` Neil Horman
[not found] ` <20141001111346.GD21151-B26myB8xz7F8NnZeBjwnZQMhkBWG/bsMQH7oEaQurus@public.gmane.org>
2014-10-01 23:33 ` Hiroshi Shimamoto
[not found] ` <7F861DC0615E0C47A872E6F3C5FCDDBD02AE422F-ZmjkEB1lVlLt6d3pZDjeaEtBU8KWyXPq@public.gmane.org>
2014-10-02 2:01 ` Neil Horman
[not found] ` <20141002020126.GA9757-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2014-10-02 2:07 ` Hiroshi Shimamoto
[not found] ` <7F861DC0615E0C47A872E6F3C5FCDDBD02AE4668-ZmjkEB1lVlLt6d3pZDjeaEtBU8KWyXPq@public.gmane.org>
2014-10-02 2:42 ` Neil Horman
2014-10-01 11:09 ` Neil Horman
2014-09-30 14:38 ` Xie, Huawei
[not found] ` <C37D651A908B024F974696C65296B57B0F2B03A9-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2014-09-30 14:51 ` Thomas Monjalon [this message]
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