Re: [PATCH v2 4/5] fbdev: Improve performance of cfb_imageblit()

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Hi

Am 22.02.22 um 14:01 schrieb Pekka Paalanen:
> On Mon, 21 Feb 2022 20:54:09 +0100
> Thomas Zimmermann <tzimmermann@xxxxxxx> wrote:
>
> > Improve the performance of sys_imageblit() by manually unrolling
>
> sys?
>
> > the inner blitting loop and moving some invariants out. The compiler
> > failed to do this automatically. This change keeps cfb_imageblit()
> > in sync with sys_imagebit().
>
> This is correct here.
>
> > A microbenchmark measures the average number of CPU cycles
> > for sys_imageblit() after a stabilizing period of a few minutes
>
> sys?
>
> > (i7-4790, FullHD, simpledrm, kernel with debugging).
> >
> > sys_imageblit(), new: 15724 cycles
>
> sys?
>
> > cfb_imageblit(): old: 30566 cycles
> >
> > In the optimized case, cfb_imageblit() is now ~2x faster than before.
> >
> > Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> > ---
> >   drivers/video/fbdev/core/cfbimgblt.c | 51 +++++++++++++++++++++++-----
> >   1 file changed, 42 insertions(+), 9 deletions(-)
>
> Just noticed some confusion in the commit message.

I copied some of the text from the other commit and I could have sworn I 
updated it. But apparently not.

Best regards
Thomas

> Thanks,
> pq

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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