SD / Filesystem write lags -- test?

Martin Langhoff martin.langhoff at
Wed Jun 23 17:47:22 EDT 2010

On Wed, Jun 23, 2010 at 5:39 PM, James Cameron <quozl at> 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).

 - 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.


 martin.langhoff at
 martin at -- School Server Architect
 - ask interesting questions
 - don't get distracted with shiny stuff  - working code first

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