From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Date: Fri, 24 Apr 2015 13:29:23 +0000 Subject: Re: simple framebuffer slower by factor of 20, on socfpga (arm) platform Message-Id: <20150424132923.GA11729@amd> List-Id: References: <20150407121247.GA29497@amd> <20150409110634.GA27407@amd> <552660C7.4020805@ti.com> <552663C2.70308@ti.com> <55277650.8070607@codeaurora.org> In-Reply-To: <55277650.8070607@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Archit Taneja Cc: Tomi Valkeinen , Geert Uytterhoeven , Marek Vasut , kernel list , Dinh Nguyen , Jean-Christophe PLAGNIOL-VILLARD , Grant Likely , Rob Herring , Jingoo Han , Rob Clark , Linux Fbdev development list , "devicetree@vger.kernel.org" , shc_work@mail.ru, linux@arm.linux.org.uk, hsweeten@visionengravers.com 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 -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html