From: Joe Perches <joe@perches.com>
To: Sudip Mukherjee <sudipm.mukherjee@gmail.com>,
Ladislav Michl <ladis@linux-mips.org>
Cc: linux-fbdev@vger.kernel.org, linux-omap@vger.kernel.org,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: Re: [PATCH] omapfb: reduce stack usage
Date: Sat, 19 Oct 2019 01:19:15 +0000 [thread overview]
Message-ID: <184cdd47d4064420b05c16f10588595c65f789e5.camel@perches.com> (raw)
In-Reply-To: <20191018223012.tkpwbo3mg5mthlnz@debian>
On Fri, 2019-10-18 at 23:30 +0100, Sudip Mukherjee wrote:
> On Fri, Oct 18, 2019 at 07:27:28PM +0200, Ladislav Michl wrote:
> > On Fri, Oct 18, 2019 at 05:30:04PM +0100, Sudip Mukherjee wrote:
> > > The build of xtensa allmodconfig is giving a warning of:
> > > In function 'dsi_dump_dsidev_irqs':
> > > warning: the frame size of 1120 bytes is larger than 1024 bytes
> > >
> > > Allocate the memory for 'struct dsi_irq_stats' dynamically instead
> > > of assigning it in stack.
> >
> > So now function can fail silently, executes longer, code is sligthly
> > bigger... And all that to silent warning about exceeding frame size.
> > Is it really worth "fixing"?
Depends if it could fail in practice due to a stack overrun.
> The only point of failure is if kmalloc() fails and if kmalloc() fails then
> there will be error prints in dmesg to tell the user that there is no
> memory left in the system. About the size bigger, it seems
> the drivers/video/fbdev/omap2/omapfb/dss/dsi.o file is smaller with the
> patch.
> This is without the patch:
> -rw-r--r-- 1 sudip sudip 316856 Oct 18 22:27 drivers/video/fbdev/omap2/omapfb/dss/dsi.o
> And this is with the patch:
> -rw-r--r-- 1 sudip sudip 316436 Oct 18 20:09 drivers/video/fbdev/omap2/omapfb/dss/dsi.o
>
> And also, objdump shows me that <dsi_dump_dsidev_irqs> was taking up 0xD7D
> bytes, and now with the patch it is taking up 0xBED bytes, thats a saving
> of 400 bytes. If it has 400 bytes of less code to execute will it not be
> faster now?
You should try compiling without all the debugging symbols (defconfig)
> But, I may be totally wrong in my thinking, and in that case, please feel
> free to reject the patch.
Without your patch:
$ objdump -x drivers/video/fbdev/omap2/omapfb/dss/dsi.o | grep dsi_dump_dsidev_irqs
00000d20 l F .text 0000061c dsi_dump_dsidev_irqs
With your patch:
$ objdump -x drivers/video/fbdev/omap2/omapfb/dss/dsi.o | grep dsi_dump_dsidev_irqs
00000d20 l F .text 00000638 dsi_dump_dsidev_irqs
next prev parent reply other threads:[~2019-10-19 1:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20191018163010epcas4p1a11973fbca0b3248dae6b5e87cdbf1f3@epcas4p1.samsung.com>
2019-10-18 16:30 ` [PATCH] omapfb: reduce stack usage Sudip Mukherjee
2019-10-18 17:27 ` Ladislav Michl
2019-10-18 22:30 ` Sudip Mukherjee
2019-10-19 1:19 ` Joe Perches [this message]
2019-10-19 9:11 ` Sudip Mukherjee
2020-01-03 12:50 ` Bartlomiej Zolnierkiewicz
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