[Click] click optimize efficiency

[Yongheng Qi]

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