From: "H. Peter Anvin" <hpa@zytor.com>
To: linux-kernel@vger.kernel.org
Subject: Re: memcpy_toio on i386 using byte writes even when n%2==0
Date: Tue, 30 May 2006 18:13:27 -0700 (PDT) [thread overview]
Message-ID: <e5iqjn$u22$1@terminus.zytor.com> (raw)
In-Reply-To: 447CE99B.7070707@shaw.ca
Followup to: <447CE99B.7070707@shaw.ca>
By author: Robert Hancock <hancockr@shaw.ca>
In newsgroup: linux.dev.kernel
> >
> > Note that there isn't any code for moving dwords because the
> > chances of gaining anything are slim (alignment may hurt).
>
> I'd say the chances of gaining something from executing half as many
> instructions on copying a large block of memory are very good indeed..
>
For something that generates I/O transactions, it's imperative to
generate the smallest possible number of transactions. Furthermore,
smaller than dword transactions aren't burstable, except at the
beginning and end of a burst.
-hpa
next prev parent reply other threads:[~2006-05-31 1:13 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <6gUec-3mb-7@gated-at.bofh.it>
[not found] ` <6gUec-3mb-5@gated-at.bofh.it>
[not found] ` <6icVy-56r-9@gated-at.bofh.it>
[not found] ` <6idov-5Tc-7@gated-at.bofh.it>
2006-05-31 0:55 ` memcpy_toio on i386 using byte writes even when n%2==0 Robert Hancock
2006-05-31 1:13 ` H. Peter Anvin [this message]
[not found] <6ined-4gY-17@gated-at.bofh.it>
[not found] ` <6ined-4gY-21@gated-at.bofh.it>
[not found] ` <6inee-4gY-23@gated-at.bofh.it>
[not found] ` <6ined-4gY-15@gated-at.bofh.it>
[not found] ` <6inxv-4U2-17@gated-at.bofh.it>
2006-06-03 23:52 ` Robert Hancock
2006-06-04 0:48 ` H. Peter Anvin
[not found] <6gMqr-8uW-23@gated-at.bofh.it>
2006-05-26 23:46 ` Robert Hancock
2006-05-29 7:38 ` H. Peter Anvin
2006-05-30 13:55 ` Chris Lesiak
2006-05-30 14:24 ` linux-os (Dick Johnson)
2006-05-26 15:29 Chris Lesiak
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