The patch titled
Time: optimize out some mults, since gcc can't avoid them
has been removed from the -mm tree. Its filename is
time-use-clocksource-abstraction-for-ntp-adjustments-optimize-out-some-mults-since-gcc-cant-avoid-them.patch
This patch was dropped because it was folded into time-use-clocksource-abstraction-for-ntp-adjustments.patch
------------------------------------------------------
Subject: Time: optimize out some mults, since gcc can't avoid them
From: john stultz <johnstul@xxxxxxxxxx>
Newsflash: GCC not as smart as once hoped.
This patch removes some mults since GCC can't figure out how.
Pointed out by Roman Zippel.
Signed-off-by: John Stultz <johnstul@xxxxxxxxxx>
Cc: Roman Zippel <zippel@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/clocksource.h | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)
diff -puN include/linux/clocksource.h~time-use-clocksource-abstraction-for-ntp-adjustments-optimize-out-some-mults-since-gcc-cant-avoid-them include/linux/clocksource.h
--- a/include/linux/clocksource.h~time-use-clocksource-abstraction-for-ntp-adjustments-optimize-out-some-mults-since-gcc-cant-avoid-them
+++ a/include/linux/clocksource.h
@@ -236,7 +236,6 @@ static inline int error_aproximation(u64
*
* Where mult_delta is the adjustment value made to mult
*
- * XXX - Hopefully gcc is smart enough to avoid the multiplies.
*/
static inline s64 make_ntp_adj(struct clocksource *clock,
cycles_t cycles_delta, s64* error)
@@ -244,27 +243,27 @@ static inline s64 make_ntp_adj(struct cl
s64 ret = 0;
if (*error > ((s64)clock->interval_cycles+1)/2) {
/* calculate adjustment value */
- int adjustment = 1 << error_aproximation(*error,
+ int adjustment = error_aproximation(*error,
clock->interval_cycles);
/* adjust clock */
- clock->mult += adjustment;
- clock->interval_snsecs += clock->interval_cycles * adjustment;
+ clock->mult += 1 << adjustment;
+ clock->interval_snsecs += clock->interval_cycles << adjustment;
/* adjust the base and error for the adjustment */
- ret = -(cycles_delta * adjustment);
- *error -= clock->interval_cycles * adjustment;
+ ret = -(cycles_delta << adjustment);
+ *error -= clock->interval_cycles << adjustment;
/* XXX adj error for cycle_delta offset? */
} else if ((-(*error)) > ((s64)clock->interval_cycles+1)/2) {
/* calculate adjustment value */
- int adjustment = 1 << error_aproximation(-(*error),
+ int adjustment = error_aproximation(-(*error),
clock->interval_cycles);
/* adjust clock */
- clock->mult -= adjustment;
- clock->interval_snsecs -= clock->interval_cycles * adjustment;
+ clock->mult -= 1 << adjustment;
+ clock->interval_snsecs -= clock->interval_cycles << adjustment;
/* adjust the base and error for the adjustment */
- ret = cycles_delta * adjustment;
- *error += clock->interval_cycles * adjustment;
+ ret = cycles_delta << adjustment;
+ *error += clock->interval_cycles << adjustment;
/* XXX adj error for cycle_delta offset? */
}
return ret;
_
Patches currently in -mm which might be from johnstul@xxxxxxxxxx are
time-clocksource-infrastructure.patch
time-use-clocksource-infrastructure-for-update_wall_time.patch
time-let-user-request-precision-from-current_tick_length.patch
time-use-clocksource-abstraction-for-ntp-adjustments.patch
time-use-clocksource-abstraction-for-ntp-adjustments-optimize-out-some-mults-since-gcc-cant-avoid-them.patch
time-introduce-arch-generic-time-accessors.patch
hangcheck-remove-monotomic_clock-on-x86.patch
time-i386-conversion-part-1-move-timer_pitc-to-i8253c.patch
time-i386-conversion-part-2-rework-tsc-support.patch
time-i386-conversion-part-3-enable-generic-timekeeping.patch
time-i386-conversion-part-4-remove-old-timer_opts-code.patch
time-i386-clocksource-drivers.patch
time-i386-clocksource-drivers-pm-timer-doesnt-use-workaround-if-chipset-is-not-buggy.patch
time-i386-clocksource-drivers-pm-timer-doesnt-use-workaround-if-chipset-is-not-buggy-acpi_pm-cleanup.patch
time-i386-clocksource-drivers-pm-timer-doesnt-use-workaround-if-chipset-is-not-buggy-acpi_pm-cleanup-fix-missing-to-rename-pmtmr_good-to-acpi_pm_good.patch
time-i386-clocksource-drivers-fix-spelling-typos.patch
time-rename-clocksource-functions.patch
make-pmtmr_ioport-__read_mostly.patch
generic-time-add-macro-to-simplify-hide-mask.patch
time-fix-time-going-backward-w-clock=pit.patch
fix-and-optimize-clock-source-update.patch
gtod-add-scx200-hrt-clocksourcediff.patch
-
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