From: "H. Peter Anvin" <hpa@zytor.com>
To: Gabriel Paubert <paubert@iram.es>
Cc: linux-kernel@vger.kernel.org
Subject: Re: TCP Segmentation Offloading (TSO)
Date: Wed, 04 Sep 2002 15:41:19 -0700 [thread overview]
Message-ID: <3D768C0F.7040006@zytor.com> (raw)
In-Reply-To: Pine.LNX.4.33.0209050027270.7673-100000@gra-lx1.iram.es
Gabriel Paubert wrote:
> On 3 Sep 2002, H. Peter Anvin wrote:
>
> [Sorry HPA, I forgot to cc to linux-kernel the first time.]
>
>
>>>P.S.
>>> Using "bswap" is little bit tricky.
>>>
>>
>>It needs to be protected by CONFIG_I486 and alternate code implemented
>>for i386 (xchg %al,%ah; rol $16,%eax, xchg %al,%ah for example.)
>
>
> While it would work, this sequence is overkill. Unless I'm mistaken, the
> only property of bswap which is used in this case is that it swaps even
> and odd bytes, which can be done by a simple "roll $8,%eax" (or rorl).
>
> I believe that bswap is one byte shorter than roll. In any case, using a
> rotate might be the right thing to do on other architectures.
>
And again, I think you'll find the rotate faster on at least some x86 cores.
-hpa
next prev parent reply other threads:[~2002-09-04 22:36 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-02 17:45 TCP Segmentation Offloading (TSO) Feldman, Scott
2002-09-02 18:58 ` kuznet
2002-09-03 7:42 ` Hirokazu Takahashi
2002-09-03 7:51 ` David S. Miller
2002-09-03 11:27 ` Paul Mackerras
2002-09-03 11:29 ` David S. Miller
2002-09-03 12:21 ` kuznet
2002-09-03 13:03 ` Hirokazu Takahashi
2002-09-03 13:19 ` Hirokazu Takahashi
2002-09-03 13:22 ` kuznet
2002-09-03 21:05 ` David S. Miller
2002-09-03 21:20 ` David S. Miller
2002-09-04 1:02 ` H. Peter Anvin
2002-09-04 1:54 ` David S. Miller
2002-09-04 22:39 ` Gabriel Paubert
2002-09-04 22:41 ` H. Peter Anvin [this message]
2002-09-05 2:13 ` Hirokazu Takahashi
2002-09-05 2:21 ` David S. Miller
2002-09-05 10:28 ` Gabriel Paubert
2002-09-05 11:17 ` Jamie Lokier
2002-09-05 13:21 ` Gabriel Paubert
2002-09-05 13:17 ` David S. Miller
2002-09-08 4:20 ` Hirokazu Takahashi
2002-09-08 4:29 ` H. Peter Anvin
2002-09-04 23:17 ` Alan Cox
2002-09-05 0:09 ` Jamie Lokier
2002-09-02 19:06 ` Jeff Garzik
2002-09-02 23:13 ` David S. Miller
2002-09-03 4:58 ` Jordi Ros
2002-09-03 6:52 ` David S. Miller
2002-09-03 7:26 ` Jordi Ros
2002-09-03 7:39 ` David S. Miller
[not found] <288F9BF66CD9D5118DF400508B68C4460283E564@orsmsx113.jf.intel.com.suse.lists.linux.kernel>
[not found] ` <200209021858.WAA00388@sex.inr.ac.ru.suse.lists.linux.kernel>
[not found] ` <20020903.164243.21934772.taka@valinux.co.jp.suse.lists.linux.kernel>
[not found] ` <20020903.005119.50342945.davem@redhat.com.suse.lists.linux.kernel>
2002-09-03 9:05 ` Andi Kleen
2002-09-03 10:00 ` David S. Miller
2002-09-03 10:10 ` Andi Kleen
2002-09-03 10:09 ` David S. Miller
-- strict thread matches above, loose matches on Subject: below --
2002-09-03 17:50 Feldman, Scott
2002-09-03 18:09 Manfred Spraul
2002-09-03 23:08 ` Hirokazu Takahashi
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