Re: route cache DoS testing and softirqs
From: Dipankar Sarma
Date: Wed Mar 31 2004 - 12:23:32 EST
On Tue, Mar 30, 2004 at 11:37:42PM +0200, Andrea Arcangeli wrote:
> On Tue, Mar 30, 2004 at 01:30:00PM -0800, David S. Miller wrote:
> > On Tue, 30 Mar 2004 23:14:50 +0200
> > Andrea Arcangeli <andrea@xxxxxxx> wrote:
> > > > There are no hardirqs in the case under investigation, remember?
> > >
> > > no hardirqs? there must be tons of hardirqs if ksoftirqd never runs.
> > NAPI should be kicking in for this workload, and I know for a fact it is
> > for Robert's case. There should only be a few thousand hard irqs per
> > second.
> > Until the RX ring is depleted the device's hardirqs will not be re-
> > enabled.
> then Dipankar is reproducing with a workload that is completely
> different. I've only seen the emails from Dipankar so I couldn't know it
> was a NAPI load.
> He posted these numbers:
> softirq_count, ksoftirqd_count and other_softirq_count shows -
> CPU 0 : 638240 554 637686
> CPU 1 : 102316 1 102315
> CPU 2 : 675696 557 675139
> CPU 3 : 102305 0 102305
> that means nothing runs in ksoftirqd for Dipankar, so he cannot be using
And I am not. I am still on 2.6.0 and there seems to be no NAPI support
for the e100 there. Should I try 2.6.4 where e100 has NAPI support ?
Anyway, even without softirqs on the back of hardirqs, there are
other ways of softirq overload as seen in Robert's setup.
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