[Click] click optimize efficiency

[Yongheng Qi]

By the way, I used kernel version is 2.6.26.5

On 12/1/09, Yongheng Qi <jetever at gmail.com> wrote:
> Dear Cliff and friends:
>
> Today, I test the click efficiency without driver, it's work very well.
> your
> point is right, thanks.
>
> but both ethernet and wireless lead to cpu high loading. so I trace the
> element ToDevice code:
>
> ret = _dev->hard_start_xmit(skb1, _dev);
>
> this line send packet throuth driver. if don't excute this line. the cpu
> load is normal. if excute this line,
>
> only ToDevice(eth0) will have high cpu loading. I test ToDevice(ath0) too,
> the issue like ToDevice(eth0) too.
>
> I don't know click ToDevice use hard_start_xmit. why have the strange
> problem? the hard_start_xmit in the kernel is
>
> diffient with dev_queue_xmit. I guess in the ToDevice use interrupt have
> some conflict with kernel.
>
> how to solve the problem?
>
> Thanks
>
>
> 2009/11/30 Cliff Frey <cliff at meraki.com>
>
>> IRQ time is likely time spent in interrupt handlers... most likely your
>> drivers (ethernet and wireless) both install interrupt handlers.  This is
>> _not_ time spent in click.  This is time spent in your drivers.
>>
>> Softirq time is generally time spent in tasklets, either explicit
>> tasklets
>> used by drivers or by rx_poll functions.  Again, this is time spent in
>> your
>> driver, not in click.
>>
>> If you want to choose what to optimize, then you must do what I suggested
>> in the first email, and measure the performance of each part of your
>> system
>> individually.  You could replace FromDevice with InfiniteSource and
>> ToDevice
>> with (Counter -> Discard) and see what byte/packet rate click can achieve
>> on
>> its own.
>>
>> You could run
>>
>> InfiniteSource -> Counter -> ToDevice
>>
>> And see how many packets/bytes per second your drivers are capable of
>> sending.
>>
>> Either way, I feel like your measurements indicate that it is not a click
>> performance problem, but in fact a driver performance problem.
>>
>> Good luck,
>>
>> Cliff
>>
>>
>> On Sun, Nov 29, 2009 at 5:01 AM, Yongheng Qi <jetever at gmail.com> wrote:
>>
>>> Dear Cliff
>>>
>>> My system use FromDevice get packet from wireless and ethernet driver.
>>> you
>>> mean FromDeivce used interrupt is irq but not the softirq?
>>>
>>> I can't distinguish between irq and softirq at driver , FromDevice and
>>> ToDevice.
>>>
>>> 2009/11/29 Cliff Frey <cliff at meraki.com>
>>>
>>>> 56% softirq implies to me that 56% of the time is spent in the packet
>>>> receive functions in your ethernet or wireless driver.... as click
>>>> should
>>>> not be running at softirq context.  15% irq means that 15% of the time
>>>> is
>>>> actually in interrupt handlers, again that is likely your wireless
>>>> and/or
>>>> ethernet drivers.  So I don't think that your performance problem is in
>>>> kclick itself.  Probably you could get 10% better performance if you
>>>> were
>>>> able to get rid of many many click elements in your data path... but I
>>>> really think that you should be looking at your ethernet/wireless
>>>> drivers
>>>> instead.
>>>>
>>>>
>>>> As I said in my earlier email, you need to break down your problem into
>>>> smaller pieces before you can blame kclick for the performance.  You
>>>> could
>>>> also enable CONFIG_PROFILE in linux, which could give you insight into
>>>> how
>>>> much time your drivers are spending on what lines of code... but it is
>>>> a
>>>> fair amount of work.  In addition, with some work you can get linux to
>>>> also
>>>> profile your kernel modules... for instance:
>>>> http://lkml.indiana.edu/hypermail/linux/kernel/0405.1/1115.html
>>>>
>>>> Good luck.
>>>>
>>>> Cliff
>>>>
>>>>
>>>> On Sat, Nov 28, 2009 at 12:50 AM, Yongheng Qi <jetever at gmail.com>
>>>> wrote:
>>>>
>>>>> I tested the NotifierQueue,  the instance is the same as before.
>>>>>
>>>>> anyone have ideas? Thanks.
>>>>>
>>>>> This is the top result:
>>>>>
>>>>> Mem: 20540K used, 106700K free, 0K shrd, 0K buff, 6656K cached
>>>>> CPU:   0% usr  27% sys   0% nice   0% idle   0% io  15% irq  56%
>>>>> softirq
>>>>> Load average: 0.95 0.88 0.50
>>>>>  PID  PPID USER     STAT   VSZ %MEM %CPU COMMAND
>>>>>  777     2 root     RW       0   0%  99% [kclick]
>>>>>  807   691 root     R     1960   2%   0% top
>>>>>  682   664 root     S     1992   2%   0% /usr/sbin/dropbear -p 22
>>>>>  691   682 root     S     1972   2%   0% -ash
>>>>>
>>>>>
>>>>
>>>
>>>
>>> --
>>> Yongheng Qi
>>>
>>> Mobile: +86 1390 119 7481
>>>
>>
>>
>
>
> --
> Yongheng Qi
>
> Mobile: +86 1390 119 7481
>

-- 
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Yongheng Qi

Mobile: +86 1390 119 7481