From mboxrd@z Thu Jan  1 00:00:00 1970
From: linus.walleij@linaro.org (Linus Walleij)
Date: Mon, 27 Jun 2011 17:29:54 +0200
Subject: [PATCH v6 00/11] mmc: use nonblock mmc requests to minimize
	latency
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On Mon, Jun 27, 2011 at 12:02 PM, Russell King - ARM Linux
<linux@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?

Thanks,
Linus Walleij