Re: [RFC] IPV4 long lasting timer function

[Lee Revell <rlrevell@joe-job.com>]

On Wed, 2005-08-17 at 22:59 +0200, Thomas Gleixner wrote:
> Hi,
> 
> while tracking down some timer related ugliness I stumbled over the
> timer driven function rt_secret_rebuild(), which does a loop over
> rt_has_mask (1024 in my case) entries and possibly some subsequent
> variable sized loops inside each step.
> 
> On a 300MHZ PPC system this accumulated to a worst case total of >5ms. I
> could not reproduce it with this magnitude, but applying heavy
> networking load is definitely triggering this behaviour.
> 
> Shouldn't this be converted to a workqueue, which gets triggered by a
> timer instead of blocking the timer softirq and therefor the delivery of
> other timer functions that long ?

Wow, blast from the past!  This was one of the very first problematic
code paths Ingo and I identified in the early days of the voluntary
preempt patch (using the crude ALSA xrun debug mechanism which was the
best we had before /proc/latency_trace).

IIRC I was able to trivially reproduce it by leaving gtk-gnutella
running overnight with a few active searches/downloads.

Lee