Re: calibrate_migration_costs takes ages on s390

[Olaf Hering]

 On Mon, Feb 13, Ingo Molnar wrote:

> 
> * Heiko Carstens <heiko.carstens@xxxxxxxxxx> wrote:
> 
> > The boot sequence on s390 sometimes takes ages and we spend a very 
> > long time (up to one or two minutes) in calibrate_migration_costs. The 
> > time spent there differs from boot to boot. Also the calculated costs 
> > differ a lot. I've seen differences by up to a factor of 15 (yes, 
> > factor not percent). Also I doubt that making these measurements make 
> > much sense on a completely virtualized architecture where you cannot 
> > tell how much cpu time you will get anyway. Is there any workaround or 
> > fix available so we can avoid seeing this?
> 
> which is the precise kernel version used? We toned down calibration a 
> bit recently.

We did a bit of testing, -rc2-git3 + the patch below was still ok.

 [PATCH] s390: earlier initialization of cpu_possible_map
 9733e2407ad2237867cb13c04e7d619397fa3090

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/