2010-12-21 13:31:07 PATA and CF performance

Wojtek Skulski (UNITED STATES)

Message: 96920

Hi:

at the bottom of the PATA driver page there are benchmarks which seem to indicate that the PATA throughput is about 5 to 6 MB/s. It is pretty low compared with the theoretical PATA throughput which is much higher according both to the Wikipedia and the common experience. Any idea why the reported throughput is so low?

docs.blackfin.uclinux.org/doku.php?id=linux-kernel:drivers:pata_platform#pata_performance_test_on_bf537

Any idea whether the CF card performance is any better? The CF page does not show any performance numbers:

docs.blackfin.uclinux.org/doku.php?id=linux-kernel:drivers:bfin_cf_pcmcia

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2010-12-21 13:42:23 Re: PATA and CF performance

Mike Frysinger (UNITED STATES)

Message: 96921

not sure why this is surprising. the device is memory mapped to the async bus and there's no dma. i imagine if you bump up the SCLK and make sure the async timings are tuned, you might be able to speed up a bit.

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2010-12-21 13:49:52 Re: PATA and CF performance

Wojtek Skulski (UNITED STATES)

Message: 96922 Mike:

thanks. Is DMA supported in this driver? If not, is it possible to

add DMA, or is DMA to PATA not possible for some reason?

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2010-12-21 18:58:32 Re: PATA and CF performance

Mike Frysinger (UNITED STATES)

Message: 96927

the common pata_platform.c driver is purely PIO. perhaps it would be possible to add DMA to it ... i dont know of any reason off the top of my head it wouldnt be possible. we dont have any plans to extend this though.

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2010-12-21 19:23:42 Re: PATA and CF performance

Wojtek Skulski (UNITED STATES)

Message: 96928 Mike:

thank you. That's what I thought, but wanted to make sure.

Any idea about the CF performance?

Wojtek

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2010-12-21 19:26:52 Re: PATA and CF performance

Mike Frysinger (UNITED STATES)

Message: 96929

i doubt it'd be significantly different, but really i havent a clue. ive never done performance testing on either.