Re: [LAD] rtirq script is broken with 2.6.31

From: Rui Nuno Capela <rncbc@email-addr-hidden>
Date: Fri Aug 07 2009 - 17:01:02 EEST

Rui Nuno Capela wrote:
> Robin Gareus wrote:
>> Rui Nuno Capela wrote:
>>
>>> this issue on 2.6.31-rt has been already reported privately and i'll get
>>> to it as soon i get back home from vacation. meanwhile, it really looks
>>> like a regex trickery is all that's needed,
>> I'm not so sure, Since 2.6.31 it is also possible to raise the priority
>> not by IRQ number but by /device-driver/.
>>
>> ie:
>> PID CLS RTPRIO NI PRI %CPU STAT COMMAND
>> 9092 FF 89 - 129 0.4 S< irq/17-HDA Inte
>> 1447 FF 50 - 90 0.1 S< irq/17-uhci_hcd
>> 9093 FF 50 - 90 0.0 S< irq/17-ohci1394
>>
>> ..but of course that's also just regexp trickery ;)
>>
>> Note that the kernel limits the IRQ process name to 15 chars.
>> "HDA Inte" won't read "HDA Intel" even when using `ps -w..`
>>
>> But '/proc/interrupts' says:
>> 17: 17215454 873204 IO-APIC-fasteoi uhci_hcd:usb3, HDA Intel,
>> ohci1394
>>
>>> keeping in mind that
>>> backward compability with pre-2.6.31-rt kernels is in order (eg. i do
>>> still run on 2.56.29.5-rt22 for which the current rtirq script is
>>> perfect, of course)
>>> as a quick suggestion, try this for instance (re. line 120):
>>> PIDS=`ps -eo pid,comm | egrep "(IRQ.${IRQ}|irq\/${IRQ}\-.+)\$" | awk
>>> '{print $1}'`
>>
>> That works, but raises all devices on a given IRQ-line and results in:
>> PID CLS RTPRIO NI PRI %CPU STAT COMMAND
>> 1447 FF 88 - 128 0.1 S< irq/17-uhci_hcd
>> 9092 FF 87 - 127 0.4 S< irq/17-HDA Inte
>> 9093 FF 86 - 126 0.0 S< irq/17-ohci1394
>>
>
> which is the exact and old behavior of rtirq for kernel-rt < 2.6.31-rt.
>
> this time however it looks that you can actually improve things when
> several device drivers are hanging on a irq line. that is, one can tune
> up the one and only the one actually intended (eg. "snd" => "irq/17-HDA
> Inte" and nothing else)
>
> not just a simple regex oneliner anymore and i'm afraid it might need a
> deeper retouch...
>

not so deeper, more than a simple regex fix but some bash trickery now
added: please, try the attached patch (rtirq-20090807-1.diff) and tell ;)

cheers

-- 
rncbc aka Rui Nuno Capela
rncbc@email-addr-hidden


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Received on Fri Aug 7 20:15:02 2009

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