Re: [announce] [patch] limiting IRQ load, irq-rewrite-2.4.11-B5

From: BALBIR SINGH (balbir.singh@wipro.com)
Date: Thu Oct 04 2001 - 04:19:32 EST


Ingo, is it possible to provide an interface (optional interface) to drivers,
so that they can decide how many interrupts are too much. Drivers who feel
that they should go in for interrupt mitigation have the option of deciding
to go for it.

Ofcourse, you could also have a ceiling on the maximun number of interrupts,
but the ceiling should be user configurable (using sysctl or /proc), this
would enable administrators to config their systems depending on what kind
of devices (with shared interrupts or not) they have.

Just my 2cents,
Balbir

Ingo Molnar wrote:

>On Wed, 3 Oct 2001, Linus Torvalds wrote:
>
>>Now test it again with the disk interrupt being shared with the
>>network card.
>>
>>Doesn't happen? It sure does. [...]
>>
>
>yes, disk IRQs might be delayed in that case. Without this mechanizm there
>is a lockup.
>
>>Which is why I like the NAPI approach. If somebody overloads my
>>network card, my USB camera doesn't stop working.
>>
>
>i agree that NAPI is a better approach. And IRQ overload does not happen
>on cards that have hardware-based irq mitigation support already. (and i
>should note that those cards will likely perform even faster with NAPI.)
>
>>I don't disagree with your patch as a last resort when all else fails,
>>but I _do_ disagree with it as a network load limiter.
>>
>
>okay - i removed those parts already (kpolld) in today's patch. (It
>initially was an experiment to prove that this is the only problem we are
>facing under such loads.)
>
> Ingo
>
>-
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