[PATCH v6 00/11] mmc: use nonblock mmc requests to minimize latency

Linus Walleij linus.walleij at linaro.org
Mon Jun 27 11:29:54 EDT 2011

On Mon, Jun 27, 2011 at 12:02 PM, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:

> The next thing to think about in DMA-land is whether we should total up
> the size of the SG list and choose whether to flush the individual SG
> elements or do a full cache flush.  There becomes a point where the full
> cache flush becomes cheaper than flushing each SG element individually.

We noticed that even for a single (large) buffer, any cache flush operation
above a certain threshold flushing indiviudal lines become more expensive
than flushing the entire cache.

I requested colleagues to look into implenting this threshold in the
arch/arm/mm/cache-v7.S file. but I think they ran into trouble and
eventually had to give up on it.

Vijay or Srinidhi, can you share your findings?

Linus Walleij

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