possible memory leak or memory waste

Tue May 26 00:23:25 PDT 2015

Am 26.05.2015 um 07:42 schrieb Michal Kazior:
> On 26 May 2015 at 02:07, Sebastian Gottschall <s.gottschall at dd-wrt.com> wrote:
>> Am 26.05.2015 um 01:42 schrieb Ben Greear:
>>> Can you test with ath9k to make sure it is actually ath10k related?
>> already tested. this device has 2 chipsets. one is ath9k based and the
>> second is ath10k based. :-)
>> only if i kill the hostapd process which controls ath10k. the memory waste
>> is gone
> Keep in mind that hostapd itself requires memory to function as well.
> Each process (and thread) need some internal kernel memory (stack, et
> al).
>
i know. 1.8 mb is what i see in userspace. the ath9k and ath10k 
controling hostapd uses the same amount of memory.
no difference between them. 50 mb is never taken by hostapd.
consider that this embedded device  has just 64 mb ram. (dlink-dir859)

>
>> yes. slowly. its fluctuating. so sometimes there is 30 mb free again and
>> seconds later just 2 mb. so very heavy changes. on bigger routers with more
>> than 64 mb (i have a second here with 128 mb)
>> the total consumption stabilizes at 45 - 50 mb for the driver only which is
>> still too much for sure.  so it may not a leak. but ath10k or the firmware
>> is wasting too much memory for embedded devices
>> and ar9880 is just used on embedded devices almost
> Using `free` is a pretty poor way of assessing memory usage of a
> kernel driver. It reports how much the OS has memory available to
> userspace immediately (kernel recycles some memory for performance
> reasons, e.g. SLAB does it). There's a lot of metadata too so what you
> actually see is many other things that involve ath10k being used.
i checked meminfo as well. but you dont see any differences in it. it 
shows only differences in the same values as free.
all other slab related info etc are not changing.
>
> The driver itself should be consuming around 5MB of memory at idle
> (interface up, no significant traffic). Most of this goes for the Rx
> ring which has 1023*1920 bytes (+/- allocation and metadata waste).
> Then there's a bunch of CE buffers as well which take up some memory
> (used for driver-firmware communication), e.g. 2048*512 + 2048*128
> (HTT and WMI, both target->host).
>
> When Txing it may eat up additional 1424 * (MSDU size +
> sizeof(skbuff)). Note that Tx queues can be longer - driver isn't
> aware of qdiscs and those can store frames as well.
>
> 11ac supports frame aggregates going up to 1MB so these queues pretty
> much need to be this long if you want to be able to get highest
> possible throughput.
yes. but ath10k has its main usage on embedded devices. at least for 
AR9880 chipsets
since there is not even a windows driver available for AR9880.
so now consider that ath10k is not able to run on devices with good 
stability, where the QCA LSDK Driver
does not seem to have that big resource problem.
so it doesnt make much sense to go on here in this way.
this resource problem must be solved. about 50 MB is really too much.


Sebastian
>
>
> Michał
>
>>> Thanks,
>>> Ben
>>>
>>>
>>> On 05/25/2015 04:00 PM, Sebastian Gottschall wrote:
>>>> Am 26.05.2015 um 00:39 schrieb Ben Greear:
>>>>> Default firmware has a hard-coded minimum number of tx buffers
>>>>> (somewhere
>>>>> more than 1k buffers I think).  Maybe driver is allocating all this
>>>>> memory somehow?
>>>>>
>>>>> If you do one-way traffic tests (udp), I wonder if you can tell if it is
>>>>> tx
>>>>> or rx that consumes the memory?
>>>> its tx. i have a ethernet over ip tunnel running on that link and i
>>>> broadcast iptv in that way. (its my way to convert multicast to unicast)
>>>> the  tunnel itself is rfc ethernet over ip, which is somewhat like udp.
>>>> so connectionless protocol
>>>>
>>>> Sebastian
>>>>>
>>>>> CT firmware can be configured to use any multiple-of-8 amount of tx
>>>>> buffers, though I have not tested below around 600.
>>>>>
>>>>> Thanks,
>>>>> Ben
>>>>>
>>>>> On 05/25/2015 02:26 PM, Sebastian Gottschall wrote:
>>>>>> today using the latest testing driver, i found out the memory
>>>>>> consumption is unbelievable high.
>>>>>> my router here has 64 mb ram. this ram is fully taken after some
>>>>>> minutes by ath10k. but only if data flow present.
>>>>>>
>>>>>> here the results of "free" after some minutes
>>>>>> root at DD-WRT:~# free
>>>>>> total         used         free       shared      buffers
>>>>>> Mem:         61636        58752         2884            0 2600
>>>>>> -/+ buffers:              56152         5484
>>>>>> Swap:            0            0            0
>>>>>>
>>>>>>
>>>>>> now i terminate hostapd which controls the ath10k chipset
>>>>>>
>>>>>>
>>>>>> root at DD-WRT:~# kill 902
>>>>>> root at DD-WRT:~# free
>>>>>> total         used         free       shared      buffers
>>>>>> Mem:         61636        23212        38424            0 2416
>>>>>> -/+ buffers:              20796        40840
>>>>>> Swap:            0            0            0
>>>>>>
>>>>>>
>>>>>> you see the difference?
>>>>>>
>>>>>>
>>>>>> regards,
>>>>>> Sebastian Gottschall
>>>>>>
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>>
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