Date: Fri, 24 Apr 2015 15:29:23 +0200
From: Pavel Machek <pavel@ucw.cz>
To: Archit Taneja <architt@codeaurora.org>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Marek Vasut <marek.vasut@gmail.com>,
        kernel list <linux-kernel@vger.kernel.org>,
        Dinh Nguyen <dinh.linux@gmail.com>,
        Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>,
        Grant Likely <grant.likely@linaro.org>,
        Rob Herring <robh+dt@kernel.org>, Jingoo Han <jg1.han@samsung.com>,
        Rob Clark <robdclark@gmail.com>,
        Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        shc_work@mail.ru, linux@arm.linux.org.uk, hsweeten@visionengravers.com
Subject: Re: simple framebuffer slower by factor of 20, on socfpga (arm)
 platform
Message-ID: <20150424132923.GA11729@amd>
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 <20150409110634.GA27407@amd>
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 <552663C2.70308@ti.com>
 <55277650.8070607@codeaurora.org>
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Hi!

On Fri 2015-04-10 12:35:52, Archit Taneja wrote:
> >That said, if the fb is in RAM, and is only written by the CPU, I think
> >a normal memcpy() for fb_memcpy_fromfb() should be fine...
> 
> I didn't test for performance regressions when I posted this patch.
> 
> A look at _memcpy_fromio in arch/arm/kernel/io.c shows that readb() is used
> all the time, even when the source and destination addresses are aligned for
> larger reads to be possible. Other archs seem to use readl() or readq() when
> they can. Maybe that makes memcpy_fromio slower than the implementation of
> memcpy on arm?

Ok, can you prepare a patch for me to try? Or should we just revert
the original commit?
									Pavel
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