[PATCH] Add num_to_str() for speedup /proc/stat

[KAMEZAWA Hiroyuki]

On Thu, 26 Jan 2012 17:18:00 -0800
Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:

> On Fri, 27 Jan 2012 10:09:33 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> 
> > > I expect most of these numbers are zero.  I wonder if we would get
> > > useful speedups from
> > > 
> > > 	for_each_irq_nr(j) {
> > > 		/* Apologetic comment goes here */
> > > 		if (kstat_irqs(j))
> > > 			seq_printf(p, " %u", kstat_irqs(j));
> > > 		else
> > > 			seq_puts(p, " 0");
> > > 	}
> > 
> > Yes. This is very good optimization and shows much optimization.
> > I did this at first try  but did complicated ones because it seems
> > not interesting. (This is my bad habit...)
> > 
> > I'll try again and measure time.
> 
> seq_puts() is too slow ;)  I bet seq_putc(p, ' ');seq_putc(p, '0') will
> complete in negative time.


How about this ? I think this is simple enough.
=