On Tue, 06 Jul 2010 18:13:58 -0400 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> On Tue, 2010-07-06 at 09:51 +0900, KOSAKI Motohiro wrote:
> > Andrew Morton pointed out almost sched_setscheduler() caller are
> > using fixed parameter and it can be converted static. it reduce
> > runtume memory waste a bit.
>
> We are replacing runtime waste with permanent waste?
Confused. kernel/trace/ appears to waste resources by design, so what's
the issue?
I don't think this change will cause more waste. It'll consume 4 bytes
of .data and will save a little more .text.
> >
> > Reported-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
>
>
>
> > --- a/kernel/trace/trace_selftest.c
> > +++ b/kernel/trace/trace_selftest.c
> > @@ -560,7 +560,7 @@ trace_selftest_startup_nop(struct tracer *trace, struct trace_array *tr)
> > static int trace_wakeup_test_thread(void *data)
> > {
> > /* Make this a RT thread, doesn't need to be too high */
> > - struct sched_param param = { .sched_priority = 5 };
> > + static struct sched_param param = { .sched_priority = 5 };
> > struct completion *x = data;
> >
>
> This is a thread that runs on boot up to test the sched_wakeup tracer.
> Then it is deleted and all memory is reclaimed.
>
> Thus, this patch just took memory that was usable at run time and
> removed it permanently.
>
> Please Cc me on all tracing changes.
Well if we're so worried about resource wastage then how about making
all boot-time-only text and data reside in __init and __initdata
sections rather than hanging around uselessly in memory for ever?
Only that's going to be hard because we went and added pointers into
.init.text from .data due to `struct tracer.selftest', which will cause
a storm of section mismatch warnings. Doh, should have invoked the
selftests from initcalls. That might open the opportunity of running
the selftests by modprobing the selftest module, too.
And I _do_ wish the selftest module was modprobeable, rather than this
monstrosity:
#ifdef CONFIG_FTRACE_SELFTEST
/* Let selftest have access to static functions in this file */
#include "trace_selftest.c"
#endif
Really? Who had a tastebudectomy over there? At least call it
trace_selftest.inc or something, so poor schmucks don't go scrabbling
around wondering "how the hell does this thing get built oh no they
didn't really go and #include it did they?"
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