Re: [PATCH v1] mmc: fix async request mechanism for sequential read scenarios

[Konstantin Dorfman <kdorfman@codeaurora.org>]

Hello,

On 10/26/2012 02:07 PM, Venkatraman S wrote:

> 
> Actually there could a lot of reasons why block layer or CFQ would not have
> inserted the request into the queue. i.e. you can see a lot of exit paths
> where blk_peek_request returns NULL, even though there could be any request
> pending in one of the CFQ requests queues.
> 
> Essentially you need to check what makes blk_fetch_request
> (cfq_dispatch_requests() ) return NULL when there is an element in
> queue, if at all.
> 

This is not important why block layer causes to blk_fetch_request() (or
blk_peek_request()) to return NULL to the MMC layer, but what is really
important - MMC layer should always be able to fetch the new arrived
request ASAP, after block layer notification (mmc_request() ) and this
is what my fix goes to implement.

And the fix is not changing block layer behavior.

Thanks

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Konstantin Dorfman,
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