From: Timothy Miller <miller@techsource.com>
To: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Cc: "'Daniel Forrest'" <forrest@lmcg.wisc.edu>,
"'Willy Tarreau'" <willy@w.ods.org>,
linux-kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: generic strncpy - off-by-one error
Date: Mon, 18 Aug 2003 14:41:27 -0400 [thread overview]
Message-ID: <3F411DD7.10606@techsource.com> (raw)
In-Reply-To: D069C7355C6E314B85CF36761C40F9A42E20BE@mailse02.se.axis.com
Peter Kjellerstedt wrote:
> For unaligned source or destination the "Multi copy & fill"
> would degenerate into "Multi byte fill". However, for
> architectures like ix86 and CRIS that can do unaligned long
> access, it would be a win to remove the UNALIGNED() check,
> and use long word copying all the time.
In fact, it's possible to do the copy even if the source and dest are
not aligned. It requires holding pieces of source in a register and
doing shifts. If the CPU is much faster than the memory, this can be a
huge win.
> Then whether using memset() or your filling is a win depends
> on the architecture and how many bytes needs to be filled.
> For a slow processor with little function call overhead (like
> CRIS), using memset seems to be a win almost immediately.
> However, for a fast processor like my P4, the call to memset
> is not a win until some 1500 bytes need to be filled.
What is in memset that isn't in the fill code I suggested?
next prev parent reply other threads:[~2003-08-18 18:25 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-16 21:10 generic strncpy - off-by-one error Peter Kjellerstedt
2003-08-18 18:41 ` Timothy Miller [this message]
-- strict thread matches above, loose matches on Subject: below --
2003-08-20 7:43 Peter Kjellerstedt
2003-08-16 20:08 Peter Kjellerstedt
2003-08-16 9:19 Peter Kjellerstedt
2003-08-16 10:04 ` Daniel Forrest
2003-08-18 16:40 ` Timothy Miller
2003-08-16 8:15 Peter Kjellerstedt
2003-08-16 8:41 ` Daniel Forrest
2003-08-18 16:17 ` Timothy Miller
2003-08-18 16:06 ` Timothy Miller
2003-08-15 9:54 Peter Kjellerstedt
2003-08-15 17:52 ` Timothy Miller
2003-08-15 9:53 Peter Kjellerstedt
2003-08-15 17:47 ` Timothy Miller
2003-08-14 9:34 Peter Kjellerstedt
2003-08-14 19:45 ` Willy Tarreau
2003-08-14 20:24 ` Timothy Miller
2003-08-13 3:09 Anthony Truong
2003-08-13 2:18 Albert Cahalan
2003-08-13 2:47 ` Erik Andersen
2003-08-13 3:38 ` Albert Cahalan
2003-08-13 3:56 ` Nick Piggin
2003-08-13 5:18 ` Willy Tarreau
2003-08-13 19:03 ` Timothy Miller
2003-08-12 14:07 Yoshinori Sato
2003-08-12 14:39 ` Willy Tarreau
2003-08-12 14:50 ` Yoshinori Sato
2003-08-12 15:03 ` Valdis.Kletnieks
2003-08-12 15:54 ` William Gallafent
2003-08-12 16:19 ` Valdis.Kletnieks
2003-08-12 16:09 ` Andreas Schwab
2003-08-12 1:56 Anthony Truong
2003-08-12 17:14 ` Alan Cox
2003-08-12 21:53 ` Bernd Petrovitsch
2003-08-12 1:28 Anthony Truong
2003-08-12 16:24 ` Bernd Petrovitsch
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