SD / Filesystem write lags -- test?

[Martin Langhoff]

On Wed, Jun 23, 2010 at 5:39 PM, James Cameron <quozl at laptop.org> wrote:
> My calculations were based on an invalid assumption so I'll have to
> retest.

So we don't have a test that shows the problem. Drat.

Here are my notes anyway -

 - Happy to see that the commit below made it into 2.6.31 and is in
our kernel. Wonder if tweaking MMC_SPI_BLOCKSATONCE to findthe best
outcome or just to match whatever OFW is doing helps - (update: I see
Richard's post too - maybe line up ext3/4 block size too).
   http://dev.laptop.org/git/olpc-2.6/commit/?h=olpc-2.6.31&id=5cf20aa557e8f9dd5af302b8f33972082479753a

 - Test disabling ext3/4 journalling. We have a hotspot in ext3/4
metadata ops, and it's probably doing "short writes" in a way that is
likely to drive the FTL bananas.

cheers,


m
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