From: David Laight <David.Laight@ACULAB.COM>
To: "'Joe Perches'" <joe@perches.com>,
"Colin King" <colin.king@canonical.com>,
"Jérôme Pouiller" <jerome.pouiller@silabs.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"devel@driverdev.osuosl.org" <devel@driverdev.osuosl.org>
Cc: "kernel-janitors@vger.kernel.org"
<kernel-janitors@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] staging: wfx: make a const array static, makes object smaller
Date: Mon, 19 Oct 2020 08:09:19 +0000 [thread overview]
Message-ID: <048fded745634e369fa2646f87a05ec4@AcuMS.aculab.com> (raw)
In-Reply-To: <09cd7e609324d460afdf14829baf3c2f1a9cb9cd.camel@perches.com>
From: Joe Perches
> Sent: 17 October 2020 01:12
>
> On Fri, 2020-10-16 at 23:33 +0100, Colin King wrote:
> > From: Colin Ian King <colin.king@canonical.com>
> >
> > Don't populate const array filter_ies on the stack but instead
> > make it static. Makes the object code smaller by 261 bytes.
> >
> > Before:
> > text data bss dec hex filename
> > 21674 3166 448 25288 62c8 drivers/staging/wfx/sta.o
> >
> > After:
> > text data bss dec hex filename
> > 21349 3230 448 25027 61c3 drivers/staging/wfx/sta.o
>
> Thanks.
>
> It's odd to me it's so large a change as it's only
> 24 bytes of initialization. (3 entries, each 8 bytes)
Perhaps the 'stack protector' crap?
Interestingly, loading the data from the 'readonly' section
is probably a data cache miss.
Which might end up being slower than the extra code to
update the on-stack data.
The extra code might get prefetched...
David
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next prev parent reply other threads:[~2020-10-19 8:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-16 22:33 [PATCH] staging: wfx: make a const array static, makes object smaller Colin King
2020-10-17 0:11 ` Joe Perches
2020-10-19 8:09 ` David Laight [this message]
2020-10-19 9:43 ` Jérôme Pouiller
2020-10-19 17:52 ` Christophe JAILLET
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