From: Daniel Jacobowitz <dan@debian.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Gerd Knorr <kraxel@bytesex.org>,
"Randy.Dunlap" <rddunlap@osdl.org>,
rmk@arm.linux.org.uk,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: reducing stack usage in v4l?
Date: Tue, 11 Mar 2003 10:36:49 -0500 [thread overview]
Message-ID: <20030311153649.GA13882@nevyn.them.org> (raw)
In-Reply-To: <1047400169.19262.3.camel@irongate.swansea.linux.org.uk>
On Tue, Mar 11, 2003 at 04:29:30PM +0000, Alan Cox wrote:
> On Tue, 2003-03-11 at 09:19, Gerd Knorr wrote
>
> > That is wrong, at least the 2k memset/call mentioned by Andrew. There
> > are lots of memset() calls, but they all are within the case switches
> > for the ioctls and zero out only the structs which are used in that code
> > path, so it is actually much smaller (~50 -> ~300 bytes maybe, depending
> > on the ioctl).
>
> gcc sometimes does things like allocate all the objects in case
> statements at entry time. I assume its a performance win to do so.
No, it's more likely a known GCC bug to do so. See PR middle-end/9997
if you're really curious.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer
next prev parent reply other threads:[~2003-03-11 15:26 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-03-05 5:25 reducing stack usage in v4l? Randy.Dunlap
2003-03-05 5:43 ` Andrew Morton
2003-03-05 9:15 ` Gerd Knorr
2003-03-05 9:35 ` Russell King
2003-03-05 15:34 ` Randy.Dunlap
2003-03-05 21:40 ` Jörn Engel
2003-03-11 4:27 ` Randy.Dunlap
2003-03-11 9:19 ` Gerd Knorr
2003-03-11 16:29 ` Alan Cox
2003-03-11 15:36 ` Daniel Jacobowitz [this message]
2003-03-05 11:50 ` mdew
2003-03-05 12:28 ` Gerd Knorr
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