Re: [Linaro-mm-sig] [PATCH 11/15] mm: trigger page reclaim inalloc_contig_range() to stabilize watermarks

From: Michal Nazarewicz
Date: Wed Feb 08 2012 - 04:21:27 EST


On Wed, 08 Feb 2012 03:04:18 +0100, sandeep patil <psandeep.s@xxxxxxxxx> wrote:
There's another problem I am facing with zone watermarks and CMA.

Test details:
Memory : 480 MB of total memory, 128 MB CMA region
Test case : around 600 MB of file transfer over USB RNDIS onto target
System Load : ftpd with console running on target.
No one is doing CMA allocations except for the DMA allocations done by the
drivers.

Result : After about 300MB transfer, I start getting GFP_ATOMIC
allocation failures. This only happens if CMA region is reserved.

[...]

Total memory available is way above the zone watermarks. So, we ended
up starving
UNMOVABLE/RECLAIMABLE atomic allocations that cannot fallback on CMA region.

This looks like something Mel warned me about. I don't really have a good
solution for that yet. ;/

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Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, MichaÅ âmina86â Nazarewicz (o o)
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