Re: [PATCH v2] mm: dmapool: use provided gfp flags for all dma_alloc_coherent()calls

From: Soeren Moch
Date: Wed Jan 23 2013 - 10:32:27 EST


On 19.01.2013 19:59, Andrew Lunn wrote:
Please find attached a debug log generated with your patch.

I used the sata disk and two em28xx dvb sticks, no other usb devices,
no ethernet cable connected, tuners on saa716x-based card not used.

What I can see in the log: a lot of coherent mappings from sata_mv
and orion_ehci, a few from mv643xx_eth, no other coherent mappings.
All coherent mappings are page aligned, some of them (from orion_ehci)
are not really small (as claimed in __alloc_from_pool).

I don't believe in a memory leak. When I restart vdr (the application
utilizing the dvb sticks) then there is enough dma memory available
again.

Hi Soeren

We should be able to rule out a leak. Mount debugfg and then:

while [ /bin/true ] ; do cat /debug/dma-api/num_free_entries ; sleep 60 ; done

while you are capturing. See if the number goes down.

Andrew

Now I built a kernel with debugfs enabled.
It is not clear to me what I can see from the dma-api/num_free_entries output. After reboot (vdr running) I see decreasing numbers (3453 3452 3445 3430...), min_free_entries is lower (3390). Sometimes the output is constant for several minutes ( 3396 3396 3396 3396 3396,...)

Soeren
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/