From 237ec6f2e51d2fc2ff37c7c5f1ccc9264d09c85b Mon Sep 17 00:00:00 2001 From: Colin Cross Date: Tue, 7 Aug 2012 19:05:10 +0100 Subject: ARM: 7486/1: sched_clock: update epoch_cyc on resume Many clocks that are used to provide sched_clock will reset during suspend. If read_sched_clock returns 0 after suspend, sched_clock will appear to jump forward. This patch resets cd.epoch_cyc to the current value of read_sched_clock during resume, which causes sched_clock() just after suspend to return the same value as sched_clock() just before suspend. In addition, during the window where epoch_ns has been updated before suspend, but epoch_cyc has not been updated after suspend, it is unknown whether the clock has reset or not, and sched_clock() could return a bogus value. Add a suspended flag, and return the pre-suspend epoch_ns value during this period. The new behavior is triggered by calling setup_sched_clock_needs_suspend instead of setup_sched_clock. Signed-off-by: Colin Cross Reviewed-by: Linus Walleij Signed-off-by: Russell King --- arch/arm/kernel/sched_clock.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'arch/arm/kernel/sched_clock.c') diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c index 27d186abbc06..f4515393248d 100644 --- a/arch/arm/kernel/sched_clock.c +++ b/arch/arm/kernel/sched_clock.c @@ -21,6 +21,8 @@ struct clock_data { u32 epoch_cyc_copy; u32 mult; u32 shift; + bool suspended; + bool needs_suspend; }; static void sched_clock_poll(unsigned long wrap_ticks); @@ -49,6 +51,9 @@ static unsigned long long cyc_to_sched_clock(u32 cyc, u32 mask) u64 epoch_ns; u32 epoch_cyc; + if (cd.suspended) + return cd.epoch_ns; + /* * Load the epoch_cyc and epoch_ns atomically. We do this by * ensuring that we always write epoch_cyc, epoch_ns and @@ -98,6 +103,13 @@ static void sched_clock_poll(unsigned long wrap_ticks) update_sched_clock(); } +void __init setup_sched_clock_needs_suspend(u32 (*read)(void), int bits, + unsigned long rate) +{ + setup_sched_clock(read, bits, rate); + cd.needs_suspend = true; +} + void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate) { unsigned long r, w; @@ -169,11 +181,23 @@ void __init sched_clock_postinit(void) static int sched_clock_suspend(void) { sched_clock_poll(sched_clock_timer.data); + if (cd.needs_suspend) + cd.suspended = true; return 0; } +static void sched_clock_resume(void) +{ + if (cd.needs_suspend) { + cd.epoch_cyc = read_sched_clock(); + cd.epoch_cyc_copy = cd.epoch_cyc; + cd.suspended = false; + } +} + static struct syscore_ops sched_clock_ops = { .suspend = sched_clock_suspend, + .resume = sched_clock_resume, }; static int __init sched_clock_syscore_init(void) -- cgit v1.2.3 From a42c362980430be74b77ec8f374964f61062379f Mon Sep 17 00:00:00 2001 From: Russell King Date: Sun, 9 Sep 2012 18:39:28 +0100 Subject: ARM: Add irqtime accounting support Add support for irq time accounting. This commit prepares ARM by adding the call to enable_sched_clock_irqtime() in sched_clock(). We introduce a new kernel parameter - irqtime - which takes an integer. -1 for auto, 0 for disabled, and 1 for enabled. Auto mode selects IRQ accounting if we have a sched_clock() tick rate greater than 1MHz. Frederic Weisbecker is working on a patch set which moves the IRQ_TIME_ACCOUNTING into arch/, so that part is not incorporated into this patch; this facility becomes available on ARM only when both this patch and Frederic's patches are merged. Signed-off-by: Russell King --- arch/arm/kernel/sched_clock.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'arch/arm/kernel/sched_clock.c') diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c index 27d186abbc06..9b8451a4330f 100644 --- a/arch/arm/kernel/sched_clock.c +++ b/arch/arm/kernel/sched_clock.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -25,6 +26,9 @@ struct clock_data { static void sched_clock_poll(unsigned long wrap_ticks); static DEFINE_TIMER(sched_clock_timer, sched_clock_poll, 0, 0); +static int irqtime = -1; + +core_param(irqtime, irqtime, int, 0400); static struct clock_data cd = { .mult = NSEC_PER_SEC / HZ, @@ -145,6 +149,10 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate) */ cd.epoch_ns = 0; + /* Enable IRQ time accounting if we have a fast enough sched_clock */ + if (irqtime > 0 || (irqtime == -1 && rate >= 1000000)) + enable_sched_clock_irqtime(); + pr_debug("Registered %pF as sched_clock source\n", read); } -- cgit v1.2.3