On 20.11.2012 15:31, Marek Szyprowski wrote:
dmapool always calls dma_alloc_coherent() with GFP_ATOMIC flag,
regardless the flags provided by the caller. This causes excessive
pruning of emergency memory pools without any good reason. Additionaly,
on ARM architecture any driver which is using dmapools will sooner or
later trigger the following error:
"ERROR: 256 KiB atomic DMA coherent pool is too small!
Please increase it with coherent_pool= kernel parameter!".
Increasing the coherent pool size usually doesn't help much and only
delays such error, because all GFP_ATOMIC DMA allocations are always
served from the special, very limited memory pool.
This patch changes the dmapool code to correctly use gfp flags provided
by the dmapool caller.
Reported-by: Soeren Moch <smoch@xxxxxx>
Reported-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Tested-by: Andrew Lunn <andrew@xxxxxxx>
Tested-by: Soeren Moch <smoch@xxxxxx>
Now I tested linux-3.7.1 (this patch is included there) on my Marvell
Kirkwood system. I still see
ERROR: 1024 KiB atomic DMA coherent pool is too small!
Please increase it with coherent_pool= kernel parameter!
after several hours of runtime under heavy load with SATA and
DVB-Sticks (em28xx / drxk and dib0700).
As already reported earlier this patch improved the behavior compared to
linux-3.6.x and 3.7.0 (error after several ten minutes runtime), but
I still see a regression compared to linux-3.5.x. With this kernel the
same system with same workload runs flawlessly.
Regards,
Soeren
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