Polling slows down bandwidth

[Коньков Евгений]

Zdravstvuyte, Chuck. (How do you do, Chuck ;-)


Вы писали 29 октября 2010 г., 20:23:19:

CS> On Oct 28, 2010, at 11:39 PM, Коньков Евгений wrote:
>> Здравствуйте, Chuck.

CS> Um, greetings?
yes, it is

>> Вы писали 28 октября 2010 г., 23:41:58:
>> 
>> CS> On Oct 28, 2010, at 1:21 PM, Коньков Евгений wrote:
>>>> [ ... ]
>> 
>> CS> What is "sysctl kern.clockrate", and have you increased kern.hz
>> CS> in /boot/loader.conf to at least 1000, if not 2000 or 4000?
>> 
>> # vmstat -i
>> interrupt                          total       rate
>> irq14: ata0                       193948          6
>> irq16: rl0                      42829515       1464
>> irq23: nfe0                     41224044       1409
>> cpu0: timer                     58494158       1999
>> irq256: igb0                      106911          3
>> irq257: igb0                      254606          8
>> irq258: igb0                           2          0
>> Total                          143103184       4892
>> 
>> # sysctl kern.clockrate
>> kern.clockrate: { hz = 1000, tick = 1000, profhz = 2000, stathz = 133 }
>> 
>> # sysctl kern.hz
>> kern.hz: 1000
>> but I have configured and installed kern with 2000HZ
>> "systat -v" shows that: 2002 cpu0: time

CS> Actually, the interrupt rate is tracking profile hz, which is
CS> roughly double the actual kern.hz-- per sysctl, you should try to at least double kern.hz.
ok, I will.

>> 
>> CS> Polling mode operation generally performs better when using older
>> CS> 100Mbs ethernet NICs which do not support interrupt mitigation and
>> CS> various capabilities like TSO4; gigabit ethernet NICs are smarter
>> CS> hardware and can generally outperform polling mode.
>> 
>> so using polling on gigabit NICs is a bottle neck? and is cause of low performance, is not?

CS> Simple answer is yes.  It should be possible that you could tune
CS> polling to get similar performance, or at least better performance
CS> than you see now, but the additional hardware capabilities of
CS> gigabit NICs are likely to outperform polling mode, just as
CS> polling mode can generally outperform old 100MBs ethernet NICs.

CS> Regards,



-- 
С уважением,
 Коньков                          mailto:kes-kes at yandex.ru