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SubjectRe: [PATCH v2] staging: vc04_services: Replace dmac_map_area with dmac_map_sg
On Tue, Oct 25, 2016 at 07:23:27PM -0700, Michael Zoran wrote:
> The original arm implementation uses dmac_map_area which is not
> portable. Replace it with an architecture neutral version
> which uses dma_map_sg.
>
> As you can see that for larger page sizes, the dma_map_sg
> implementation is faster then the original unportable dma_map_area
> implementation.
>
> Test dmac_map_area dma_map_page dma_map_sg
> vchiq_test -b 4 10000 51us/iter 76us/iter 76us
> vchiq_test -b 8 10000 70us/iter 82us/iter 91us
> vchiq_test -b 16 10000 94us/iter 118us/iter 121us
> vchiq_test -b 32 10000 146us/iter 173us/iter 187us
> vchiq_test -b 64 10000 263us/iter 328us/iter 299us
> vchiq_test -b 128 10000 529us/iter 631us/iter 595us
> vchiq_test -b 256 10000 2285us/iter 2275us/iter 2001us
> vchiq_test -b 512 10000 4372us/iter 4616us/iter 4123us
>
> For message sizes >= 64KB, dma_map_sg is faster then dma_map_page.
>
> For message size >= 256KB, the dma_map_sg is the fastest
> implementation.
>
> "Normal" messages sizes should be about 1MB which is beyond
> the length that this change shows a speed increase.
>
> This is v2 of the patch which includes extra WARN_ONs and
> incorporates feedback from Eric Anholt <eric@anholt.net>.
>
> Signed-off-by: Michael Zoran <mzoran@crowfest.net>
> ---
> .../interface/vchiq_arm/vchiq_2835_arm.c | 152 +++++++++++++--------
> 1 file changed, 93 insertions(+), 59 deletions(-)

Nice work!

I'd like to get an ack from Eric before applying it...

thanks,

greg k-h

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