Messages in this thread | | | From | Marek Vasut <> | Subject | Re: simple framebuffer slower by factor of 20, on socfpga (arm) platform | Date | Tue, 7 Apr 2015 16:24:45 +0200 |
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On Tuesday, April 07, 2015 at 02:19:33 PM, Geert Uytterhoeven wrote: > Hi Pavel, > > On Tue, Apr 7, 2015 at 2:12 PM, Pavel Machek <pavel@ucw.cz> wrote: > > I have an socfpga board, which uses has simple framebuffer implemented > > in the FPGA. On 3.15, framebuffer is fast: > > > > root@wagabuibui:~# time cat /dev/fb0 > /dev/null > > real 0m 0.00s > > user 0m 0.00s > > sys 0m 0.00s > > > > on 3.18, this takes 220msec. Similar slowdown exists for > > writes. Simple framebuffer did not change at all between 3.15 and > > 3.18; resource flags of the framebuffer are still same (0x200). > > > > If I enable caching on 3.18, it speeds up a bit, to 70msec or > > so... Which means problem is not only in caching. > > > > Any ideas? > > My first guess was commit 67dc0d4758e5 ("vt_buffer: drop console buffer > copying optimisations"), but this was introduced only in v4.0-rc1. > > Just in case you encounter another performance regression after upgrading > to a more modern kernel ;-)
Why don't you use the Altera VIP FB on SoCFPGA ?
Best regards, Marek Vasut
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