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timekeeping: Cache optimize struct timekeeper

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struct timekeeper is quite badly sorted for the hot readout path. Most
time access functions need to load two cache lines.

Rearrange it so ktime_get() and getnstimeofday() are happy with a
single cache line.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
Thomas Gleixner 2014-07-16 21:04:07 +00:00 • committed by John Stultz
parent c905fae43f
commit 3fdb14fd1d
2 changed files with 144 additions and 127 deletions
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86
include/linux/timekeeper_internal.h
View file

@ -10,7 +10,22 @@
#include <linux/jiffies.h>
#include <linux/time.h>
/* Structure holding internal timekeeping values. */
/*
* Structure holding internal timekeeping values.
*
* Note: wall_to_monotonic is what we need to add to xtime (or xtime
* corrected for sub jiffie times) to get to monotonic time.
* Monotonic is pegged at zero at system boot time, so
* wall_to_monotonic will be negative, however, we will ALWAYS keep
* the tv_nsec part positive so we can use the usual normalization.
*
* wall_to_monotonic is moved after resume from suspend for the
* monotonic time not to jump. We need to add total_sleep_time to
* wall_to_monotonic to get the real boot based time offset.
*
* - wall_to_monotonic is no longer the boot time, getboottime must be
* used instead.
*/
struct timekeeper {
/* Current clocksource used for timekeeping. */
struct clocksource *clock;
@ -18,6 +33,29 @@ struct timekeeper {
u32 mult;
/* The shift value of the current clocksource. */
u32 shift;
/* Clock shifted nano seconds */
u64 xtime_nsec;
/* Current CLOCK_REALTIME time in seconds */
u64 xtime_sec;
/* CLOCK_REALTIME to CLOCK_MONOTONIC offset */
struct timespec64 wall_to_monotonic;
/* Offset clock monotonic -> clock realtime */
ktime_t offs_real;
/* Offset clock monotonic -> clock boottime */
ktime_t offs_boot;
/* Offset clock monotonic -> clock tai */
ktime_t offs_tai;
/* time spent in suspend */
struct timespec64 total_sleep_time;
/* The current UTC to TAI offset in seconds */
s32 tai_offset;
/* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
struct timespec64 raw_time;
/* Number of clock cycles in one NTP interval. */
cycle_t cycle_interval;
/* Last cycle value (also stored in clock->cycle_last) */
@ -29,46 +67,16 @@ struct timekeeper {
/* Raw nano seconds accumulated per NTP interval. */
u32 raw_interval;
/* Current CLOCK_REALTIME time in seconds */
u64 xtime_sec;
/* Clock shifted nano seconds */
u64 xtime_nsec;
/* Difference between accumulated time and NTP time in ntp
* shifted nano seconds. */
s64 ntp_error;
/* Shift conversion between clock shifted nano seconds and
* ntp shifted nano seconds. */
u32 ntp_error_shift;
/*
* wall_to_monotonic is what we need to add to xtime (or xtime corrected
* for sub jiffie times) to get to monotonic time. Monotonic is pegged
* at zero at system boot time, so wall_to_monotonic will be negative,
* however, we will ALWAYS keep the tv_nsec part positive so we can use
* the usual normalization.
*
* wall_to_monotonic is moved after resume from suspend for the
* monotonic time not to jump. We need to add total_sleep_time to
* wall_to_monotonic to get the real boot based time offset.
*
* - wall_to_monotonic is no longer the boot time, getboottime must be
* used instead.
* Difference between accumulated time and NTP time in ntp
* shifted nano seconds.
*/
struct timespec64 wall_to_monotonic;
/* Offset clock monotonic -> clock realtime */
ktime_t offs_real;
/* time spent in suspend */
struct timespec64 total_sleep_time;
/* Offset clock monotonic -> clock boottime */
ktime_t offs_boot;
/* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
struct timespec64 raw_time;
/* The current UTC to TAI offset in seconds */
s32 tai_offset;
/* Offset clock monotonic -> clock tai */
ktime_t offs_tai;
s64 ntp_error;
/*
* Shift conversion between clock shifted nano seconds and
* ntp shifted nano seconds.
*/
u32 ntp_error_shift;
};
#ifdef CONFIG_GENERIC_TIME_VSYSCALL