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Commit ab6504d0 authored by Mark Salyzyn's avatar Mark Salyzyn Committed by Gagan Malvi
Browse files

ANDROID: clock_gettime(CLOCK_BOOTTIME,) slows down >20x 



clock_gettime(CLOCK_BOOTTIME,) slows down after significant
accumulation of suspend time creating a large offset between it and
CLOCK_MONOTONIC time.  The __iter_div_u64_rem() is only for the usage
of adding a few second+nanosecond times and saving cycles on more
expensive remainder and division operations, but iterates one second
at a time which quickly goes out of scale in CLOCK_BOOTTIME's case
since it was specified as nanoseconds only.

The fix is to split off seconds from the boot time and cap the
nanoseconds so that __iter_div_u64_rem does not iterate.

Signed-off-by: default avatarMark Salyzyn <salyzyn@google.com>
Bug: 72406285
Change-Id: Ia647ef1e76b7ba3b0c003028d4b3b955635adabb

Signed-off-by: default avatarstarlight5234 <ifist2834@gmail.com>
Conflicts:
	arch/arm64/kernel/vdso.c
Signed-off-by: default avatarTheSync <repo-sync@outlook.com>
parent 0c2c9fe9

arch/arm/include/asm/vdso_datapage.h

+2 −1
Original line number Diff line number Diff line
@@ -64,7 +64,8 @@ struct vdso_data { 
	u32 tz_minuteswest;	/* timezone info for gettimeofday(2) */

	u32 tz_dsttime;



	u64 btm_nsec;		/* monotonic to boot time */

	u32 btm_sec;		/* monotonic to boot time */

	u32 btm_nsec;

	/* Raw clocksource multipler */

	u32 cs_raw_mult;

	/* Raw time */

arch/arm/kernel/vdso.c

+4 −1
Original line number Diff line number Diff line
@@ -320,6 +320,8 @@ void update_vsyscall(struct timekeeper *tk) 
	vdso_data->wtm_clock_nsec		= wtm->tv_nsec;



	if (!vdso_data->use_syscall) {

		struct timespec btm = ktime_to_timespec(tk->offs_boot);



		vdso_data->cs_cycle_last	= tk->tkr_mono.cycle_last;

		vdso_data->raw_time_sec		= tk->raw_sec;

		vdso_data->raw_time_nsec	= tk->tkr_raw.xtime_nsec;
@@ -330,7 +332,8 @@ void update_vsyscall(struct timekeeper *tk) 
		/* tkr_mono.shift == tkr_raw.shift */

		vdso_data->cs_shift		= tk->tkr_mono.shift;

		vdso_data->cs_mask		= tk->tkr_mono.mask;

		vdso_data->btm_nsec		= ktime_to_ns(tk->offs_boot);

		vdso_data->btm_sec		= btm.tv_sec;

		vdso_data->btm_nsec		= btm.tv_nsec;

	}



	vdso_write_end(vdso_data);

arch/arm64/include/asm/vdso_datapage.h

+2 −1
Original line number Diff line number Diff line
@@ -45,7 +45,8 @@ struct vdso_data { 
	__u64 xtime_coarse_nsec;

	__u64 wtm_clock_sec;	/* Wall to monotonic time */

	vdso_wtm_clock_nsec_t wtm_clock_nsec;

	__u64 btm_nsec;		/* monotonic to boot time */

	__u32 btm_sec;		/* monotonic to boot time */

	__u32 btm_nsec;

	__u32 tb_seq_count;	/* Timebase sequence counter */

	/* cs_* members must be adjacent and in this order (ldp accesses) */

	__u32 cs_mono_mult;	/* NTP-adjusted clocksource multiplier */

arch/arm64/kernel/vdso.c

+4 −1
Original line number Diff line number Diff line
@@ -337,6 +337,8 @@ void update_vsyscall(struct timekeeper *tk) 
	vdso_data->wtm_clock_nsec		= tk->wall_to_monotonic.tv_nsec;



	if (!use_syscall) {

		struct timespec btm = ktime_to_timespec(tk->offs_boot);



		/* tkr_mono.cycle_last == tkr_raw.cycle_last */

		vdso_data->cs_cycle_last	= tk->tkr_mono.cycle_last;

		vdso_data->raw_time_sec         = tk->raw_sec;
@@ -347,7 +349,8 @@ void update_vsyscall(struct timekeeper *tk) 
		vdso_data->cs_raw_mult		= tk->tkr_raw.mult;

		/* tkr_mono.shift == tkr_raw.shift */

		vdso_data->cs_shift		= tk->tkr_mono.shift;

		vdso_data->btm_nsec		= ktime_to_ns(tk->offs_boot);

		vdso_data->btm_sec		= btm.tv_sec;

		vdso_data->btm_nsec		= btm.tv_nsec;

	}



	smp_wmb();

arch/arm64/kernel/vdso32/compiler.h

+2 −0
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ 
#ifndef __VDSO_COMPILER_H

#define __VDSO_COMPILER_H



#include <generated/autoconf.h>

#undef CONFIG_64BIT

#include <asm/barrier.h>	/* for isb() & dmb()	*/

#include <asm/param.h>		/* for HZ		*/

#include <asm/unistd32.h>