[U-Boot] [PATCH v2 02/12] x86: Add an accelerated memmove() function

[Simon Glass]

Hi Bin,

On 9 October 2016 at 20:05, Bin Meng <bmeng.cn at gmail.com> wrote:
> On Sat, Oct 8, 2016 at 1:53 PM, Bin Meng <bmeng.cn at gmail.com> wrote:
>> Hi Simon,
>>
>> On Sat, Oct 8, 2016 at 10:25 AM, Bin Meng <bmeng.cn at gmail.com> wrote:
>>> Hi Simon,
>>>
>>> On Thu, Oct 6, 2016 at 10:42 AM, Simon Glass <sjg at chromium.org> wrote:
>>>> Bring in a faster memmove() from Linux 4.7. This speeds up scrolling on the
>>>> display.
>>>>
>>>> Signed-off-by: Simon Glass <sjg at chromium.org>
>>>> ---
>>>>
>>>> Changes in v2:
>>>> - Move the code into string.c
>>>> - Fix multi-line comments that should not be
>>>>
>>>>  arch/x86/include/asm/string.h |   2 +-
>>>>  arch/x86/lib/string.c         | 161 ++++++++++++++++++++++++++++++++++++++++++
>>>>  2 files changed, 162 insertions(+), 1 deletion(-)
>>>>
>>>
>>> Reviewed-by: Bin Meng <bmeng.cn at gmail.com>
>>>
>>> Tested on Crown Bay with an external PCIe graphics card
>>> Tested-by: Bin Meng <bmeng.cn at gmail.com>
>>>
>>> However, I did not see significant speed up on screen scrolling...
>>>
>>
>> Crown Bay is still using cfb_console.c, which is the legacy driver
>> that does not use memmove(). Looks the new console_xxx driver is using
>> memmove(). I guess I will need convert Crown Bay to use DM video.
>>
>
> Testing shows that on Crown Bay, the DM driver with the optimized
> memmove() does not improve the performance compared to legacy
> cfb_console driver. But on Bayleybay, memmove() indeed helps the
> screen scrolling.

That's interesting. What is the difference between those two
platforms? It is slow on Crown Bay?

Regards,
Simon