check cpu_online() in nr_running()

check cpu_online() in nr_running()

[William Lee Irwin III]

nr_uninterruptible() and nr_iowait() both check cpu_online(cpu) as
cpu ranges from 0 to NR_CPUS-1; so should nr_running().


-- wli


diff -urpN linux-2.5.63/kernel/sched.c nr_running-2.5.63-1/kernel/sched.c
--- linux-2.5.63/kernel/sched.c	Thu Feb 20 20:33:52 2003
+++ nr_running-2.5.63-1/sched.c	Tue Feb 25 08:23:09 2003
@@ -637,6 +637,8 @@
 	unsigned long i, sum = 0;
 
 	for (i = 0; i < NR_CPUS; i++)
+		if (!cpu_online(i))
+			continue;
 		sum += cpu_rq(i)->nr_running;
 
 	return sum;

Re: check cpu_online() in nr_running()

[Alan Cox]

On Tue, 2003-02-25 at 16:33, William Lee Irwin III wrote:
>  	for (i = 0; i < NR_CPUS; i++)
> +		if (!cpu_online(i))
> +			continue;
>  		sum += cpu_rq(i)->nr_running;

I smell donkey poo 8)

If the change is right, which seems reasonable then I think you
need some { } 's too. Its also a hot path so it may be a lot
cleaner to keep the jump out of this by just letting
nr_running be zero for other processors ?

Re: check cpu_online() in nr_running()

[William Lee Irwin III]

On Tue, 2003-02-25 at 16:33, William Lee Irwin III wrote:
>>  	for (i = 0; i < NR_CPUS; i++)
>> +		if (!cpu_online(i))
>> +			continue;
>>  		sum += cpu_rq(i)->nr_running;

On Tue, Feb 25, 2003 at 06:32:43PM +0000, Alan Cox wrote:
> I smell donkey poo 8)

I don't really like how this stuff got arranged either.

On Tue, Feb 25, 2003 at 06:32:43PM +0000, Alan Cox wrote:
> If the change is right, which seems reasonable then I think you
> need some { } 's too. Its also a hot path so it may be a lot
> cleaner to keep the jump out of this by just letting
> nr_running be zero for other processors ?

AFAICT its only usages are in /proc/ reporting and loadavg calculation,
which aren't hotpaths per-se, but shouldn't explode in complexity.
Similar things could be said for nr_uninterruptible() and nr_iowait(),
but some kind of unusual constraint is involved wrt. hotplug.

-- wli