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

Soeren Moch
2013-01-23T15:32:44Z

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