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SubjectRe: [PATCH] init: skip calibration delay if previously done
On Fri, 03 Jun 2011 14:08:01 -0700
David Daney <ddaney@caviumnetworks.com> wrote:

> On 06/03/2011 02:00 PM, Andrew Morton wrote:
> > On Tue, 24 May 2011 16:19:06 -0700
> > Sameer Nanda<snanda@chromium.org> wrote:
> >
> >> For each CPU, do the calibration delay only once. For subsequent calls,
> >> use the cached per-CPU value of loops_per_jiffy.
> >>
> >> This saves about 200ms of resume time on dual core Intel Atom N5xx based
> >> systems. This helps bring down the kernel resume time on such systems from
> >> about 500ms to about 300ms.
> >>
> >> Signed-off-by: Sameer Nanda<snanda@chromium.org>
> >> ---
> >> init/calibrate.c | 10 +++++++++-
> >> 1 files changed, 9 insertions(+), 1 deletions(-)
> >>
> >> diff --git a/init/calibrate.c b/init/calibrate.c
> >> index 76ac919..47d3408 100644
> >> --- a/init/calibrate.c
> >> +++ b/init/calibrate.c
> >> @@ -183,11 +183,18 @@ recalibrate:
> >> return lpj;
> >> }
> >>
> >> +DEFINE_PER_CPU(unsigned long, cpu_loops_per_jiffy) = { 0 };
> >> +
> >> void __cpuinit calibrate_delay(void)
> >> {
> >> static bool printed;
> >> + int this_cpu = smp_processor_id();
> >>
> >> - if (preset_lpj) {
> >> + if (per_cpu(cpu_loops_per_jiffy, this_cpu)) {
> >> + loops_per_jiffy = per_cpu(cpu_loops_per_jiffy, this_cpu);
> >> + pr_info("Calibrating delay loop (skipped) "
> >> + "already calibrated this CPU previously.. ");
>
> That wording seems a little redundant, and there are two '.' at the end.
>
> How about:
> s/"already calibrated this CPU previously.. "/", this CPU previously
> calibrated."/
>

Pedant ;)

--- a/init/calibrate.c~init-skip-calibration-delay-if-previously-done-fix-fix
+++ a/init/calibrate.c
@@ -256,7 +256,7 @@ void __cpuinit calibrate_delay(void)
if (per_cpu(cpu_loops_per_jiffy, this_cpu)) {
loops_per_jiffy = per_cpu(cpu_loops_per_jiffy, this_cpu);
pr_info("Calibrating delay loop (skipped) "
- "already calibrated this CPU previously.. ");
+ "already calibrated this CPU");
} else if (preset_lpj) {
loops_per_jiffy = preset_lpj;
if (!printed)
_
But the whole thing is a bit weird. Does this look better?

From: Andrew Morton <akpm@linux-foundation.org>

Make these messages more gramatically pleasing, more consistent and remove
strange ellipses.

Cc: Andrew Worsley <amworsley@gmail.com>
Cc: Phil Carmody <ext-phil.2.carmody@nokia.com>
Cc: Sameer Nanda <snanda@chromium.org>
Cc: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
init/calibrate.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff -puN init/calibrate.c~init-calibratec-calibrate_delay-tidy-up-the-pr_info-messages init/calibrate.c
--- a/init/calibrate.c~init-calibratec-calibrate_delay-tidy-up-the-pr_info-messages
+++ a/init/calibrate.c
@@ -255,24 +255,24 @@ void __cpuinit calibrate_delay(void)

if (per_cpu(cpu_loops_per_jiffy, this_cpu)) {
loops_per_jiffy = per_cpu(cpu_loops_per_jiffy, this_cpu);
- pr_info("Calibrating delay loop (skipped) "
- "already calibrated this CPU");
+ pr_info("Calibrating delay loop. Skipped: already calibrated "
+ "this CPU");
} else if (preset_lpj) {
loops_per_jiffy = preset_lpj;
if (!printed)
- pr_info("Calibrating delay loop (skipped) "
- "preset value.. ");
+ pr_info("Calibrating delay loop. Skipped: "
+ "preset value");
} else if ((!printed) && lpj_fine) {
loops_per_jiffy = lpj_fine;
- pr_info("Calibrating delay loop (skipped), "
- "value calculated using timer frequency.. ");
+ pr_info("Calibrating delay loop. Skipped: value calculated "
+ "using timer frequency");
} else if ((loops_per_jiffy = calibrate_delay_direct()) != 0) {
if (!printed)
- pr_info("Calibrating delay using timer "
- "specific routine.. ");
+ pr_info("Calibrating delay loop using timer-specific "
+ "routine");
} else {
if (!printed)
- pr_info("Calibrating delay loop... ");
+ pr_info("Calibrating delay loop");
loops_per_jiffy = calibrate_delay_converge();
}
per_cpu(cpu_loops_per_jiffy, this_cpu) = loops_per_jiffy;
_


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