Re: [Xen-devel] [RFC PATCH V4 16/18] Implement 3-level event channel routines

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, 2013-03-05 at 14:28 +0000, Jan Beulich wrote:
> >>> On 05.03.13 at 13:30, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> > @@ -1546,8 +1635,11 @@ static void domain_dump_evtchn_info(struct domain *d)
> >      bitmap_scnlistprintf(keyhandler_scratch, sizeof(keyhandler_scratch),
> >                           d->poll_mask, d->max_vcpus);
> >      printk("Event channel information for domain %d:\n"
> > +           "Using %s event channel ABI\n"
> >             "Polling vCPUs: {%s}\n"
> > -           "    port [p/m]\n", d->domain_id, keyhandler_scratch);
> > +           "    port [p/m]\n",
> > +           d->domain_id, evtchn_abi_str(d->evtchn_extended),
> > +           keyhandler_scratch);
> >  
> >      spin_lock(&d->event_lock);
> >  
> 
> Afaics there's no guarding being added in the whole series against
> the dumping taking overly long. Doing this for 4,000 ports is
> already risky, but doing this for up to 256,000 ports is clearly
> too much. So without adjustment the 'e' debug key becomes
> unusable particularly on large systems (where the eventual need
> for it may be highest, as having the highest chances of running
> into problems).
> 

One solution I can think of is to print out information on per-bucket
basis, that's about 512 ports processed each time. Does this look
reasonable?


Wei.

> Jan
> 



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