From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC] ARM: kernel: io: Optimize memcpy_fromio function.
Date: Tue, 10 Sep 2013 10:05:41 +0100 [thread overview]
Message-ID: <20130910090541.GF5426@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <522DFB81.20203@gmail.com>
On Mon, Sep 09, 2013 at 05:46:57PM +0100, Dirk Behme wrote:
> Am 09.09.2013 18:20, schrieb Pardeep Kumar Singla:
> > Currently memcpy_fromio function is copying byte by byte data.
> > By replacing this function with inline assembly code, it is copying now 32 bytes at one time.
> > By running two test cases(Tested on mx6qsabresd board),results are following :-
> >
> > a)First test case by calling the memcpy_fromio function only once:-
> > 1. With Optimization it is just taking 6 usec.
> > 2. Without optimization it is taking 114usec.
> > b)Second test case by calling the memcpy_fromio function 100000 times.
> > 1.With Optimization it is just taking .8 sec
> > 2.Without optimization it is taking 11 sec.
> >
> > Signed-off-by: Pardeep Kumar Singla <b45784@freescale.com>
>
> Is there any special reason trying to optimize memcpy_fromio() itself?
> Instead of using anything like
>
> http://lists.infradead.org/pipermail/linux-arm-kernel/2013-June/173195.html
>
> ? I.e. using already existing optimized code?
Well, accessing device memory has additional restrictions over normal memory
(e.g. no unaligned access) and you may also not want to use
load/store-multiple if the device can't deal with repeated access to the
same location.
I think it's better to treat I/O separately to normal ram.
Will
prev parent reply other threads:[~2013-09-10 9:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-09 16:20 [RFC] ARM: kernel: io: Optimize memcpy_fromio function Pardeep Kumar Singla
2013-09-09 16:46 ` Dirk Behme
2013-09-09 17:30 ` Kumar Singla Pardeep-B45784
2013-09-10 9:05 ` Will Deacon [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20130910090541.GF5426@mudshark.cambridge.arm.com \
--to=will.deacon@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).