Re: performance issues (nat / conntrack)

[Harald Welte <laforge@gnumonks.org>]

On Tue, Jun 25, 2002 at 11:47:12PM +0200, Jean-Michel Hemstedt wrote:
> agreed.
> 
> (strange thing is that ethernet irq's reported by procinfo are 
>  decreasing when the machine is overloaded. It suppose that it 
>  means either that irq's are not even caught by the kernel/driver, 
>  which is quite worrying, or either that irq's counters refer to 
>  'processessed' interrupts)

are you using a driver which uses the irq mitigation interface of 2.4.x
or the NAPI of 2.5.x ?

> Harld: could you ask to your kernel specialist what is the weakpoint of
> kmem_cache_alloc()? (locks, allocs, ...), and how we could possibly
> improve it (batch alloc, but isn't it already the case?)

I don't think that the slab allocator is the bottleneck. please show me
profiling data pointing this out.

> > I've been talking about this with a couple of people here at the kernel
> > summit, and it looks like the per-packet del_timer/add_timer in
> > ip_ct_refresh should be a severe performance hit on SMP boxes.
> 
> Any indications that it would not be the same on non SMP boxes? 

well, it's still a performance problem, but on UP it doesn't involve
disabling interrupts across all cpus.

> -jmhe-

-- 
Live long and prosper
- Harald Welte / laforge@gnumonks.org               http://www.gnumonks.org/
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