Re: [PATCH wq/for-3.19 3/3] workqueue: dump workqueues on sysrq-t

[Tejun Heo <tj@kernel.org>]

(cc'ing Greg for tty)

On Mon, Dec 08, 2014 at 11:05:15AM -0800, Andrew Morton wrote:
> > Believe it or not, we already used up all alphanumerics if we count in
> > the arch-specific ones.  Given that the workqueue information would
> > primarily be useful in tracking down hangs and we'd want to see the
> > dump of tasks in that case anyway, sysrq-t isn't a bad fit for
> > appending workqueue dump.  If anybody has a better idea, I'm all ears.
> 
> Really.  Upper case?

Greg, would using uppercase chars for sysrq work over the different
types of ttys?

> > > > +static void pr_cont_pool_info(struct worker_pool *pool)
> > > > +{
> > > > +	if (pool->cpu >= 0)
> > > > +		pr_cont(" cpu=%d", pool->cpu);
> > > > +	else if (pool->node != NUMA_NO_NODE)
> > > > +		pr_cont(" node=%d", pool->node);
> > > > +
> > > > +	if (pool->cpu < 0) {
> > > > +		static char cpus_buf[PAGE_SIZE];
> > > 
> > > Ouch.  This could be [NR_CPUS + epsilon]?
> > 
> > It's bitmap mask printing so each char can show four cpus.  PAGE_SIZE
> > should be enough for now but I think we need cpumask_prcont().
> 
> I'm not concerned about it being too small ;) Not many people have 16k
> CPUs - can it be shrunk?  It's particularly gross when CONFIG_SMP=n!

Heh, lemme just go ahead and implement bitmap_pr_cont() and
cpumask_pr_cont().

Thanks.

-- 
tejun