Re: [RFC PATCH] mm: cma: add functions for getting allocation info

From: Laura Abbott
Date: Thu Dec 18 2014 - 12:00:46 EST


On 12/17/2014 2:10 PM, Gregory Fong wrote:
These functions allow for retrieval of information on what is allocated from
within a given CMA region. It can be useful to know the number of distinct
contiguous allocations and where in the region those allocations are located.

Based on an initial version by Marc Carino <marc.ceeeee@xxxxxxxxx> in a driver
that used the CMA bitmap directly; this instead moves the logic into the core
CMA API.

Signed-off-by: Gregory Fong <gregory.0xf0@xxxxxxxxx>
---
This has been really useful for us to determine allocation information for a
CMA region. We have had a separate driver that might not be appropriate for
upstream, but allowed using a user program to run CMA unit tests to verify that
allocations end up where they we would expect. This addition would allow for
that without needing to expose the CMA bitmap. Wanted to put this out there to
see if anyone else would be interested, comments and suggestions welcome.


Information is definitely useful but I'm not sure how it's intended to
be used. Do you have a sample usage of these APIs? Another option might
be to just add regular debugfs support for each of the regions instead
of just calling out to a separate driver.

Thanks,
Laura

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