linux-toradex.git/arch/arm/kernel/perf_event_xscale.c, branch v3.0.2 Linux kernel for Apalis and Colibri modules ARM: 6835/1: perf: ensure overflows aren't missed due to IRQ latency 2011-03-26T10:06:09+00:00 Will Deacon will.deacon@arm.com 2011-03-25T16:12:37+00:00 a737823d37666255e3e74ce84bc9611a038e0888 If a counter overflows during a perf stat profiling run it may overtake the last known value of the counter: 0 prev new 0xffffffff |----------|-------|----------------------| In this case, the number of events that have occurred is (0xffffffff - prev) + new. Unfortunately, the event update code will not realise an overflow has occurred and will instead report the event delta as (new - prev) which may be considerably smaller than the real count. This patch adds an extra argument to armpmu_event_update which indicates whether or not an overflow has occurred. If an overflow has occurred then we use the maximum period of the counter to calculate the elapsed events. Acked-by: Jamie Iles <jamie@jamieiles.com> Reported-by: Ashwin Chaugule <ashwinc@codeaurora.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
If a counter overflows during a perf stat profiling run it may overtake
the last known value of the counter:

    0        prev     new                0xffffffff
    |----------|-------|----------------------|

In this case, the number of events that have occurred is
(0xffffffff - prev) + new. Unfortunately, the event update code will
not realise an overflow has occurred and will instead report the event
delta as (new - prev) which may be considerably smaller than the real
count.

This patch adds an extra argument to armpmu_event_update which indicates
whether or not an overflow has occurred. If an overflow has occurred
then we use the maximum period of the counter to calculate the elapsed
events.

Acked-by: Jamie Iles <jamie@jamieiles.com>
Reported-by: Ashwin Chaugule <ashwinc@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: 6521/1: perf: use raw_spinlock_t for pmu_lock 2010-12-04T11:18:08+00:00 Will Deacon will.deacon@arm.com 2010-12-02T17:01:49+00:00 961ec6daa7b14f376c30d447a830fa4783a2112c For kernels built with PREEMPT_RT, critical sections protected by standard spinlocks are preemptible. This is not acceptable on perf as (a) we may be scheduled onto a different CPU whilst reading/writing banked PMU registers and (b) the latency when reading the PMU registers becomes unpredictable. This patch upgrades the pmu_lock spinlock to a raw_spinlock instead. Reported-by: Jamie Iles <jamie@jamieiles.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
For kernels built with PREEMPT_RT, critical sections protected
by standard spinlocks are preemptible. This is not acceptable
on perf as (a) we may be scheduled onto a different CPU whilst
reading/writing banked PMU registers and (b) the latency when
reading the PMU registers becomes unpredictable.

This patch upgrades the pmu_lock spinlock to a raw_spinlock
instead.

Reported-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: 6512/1: perf: fix warnings generated by sparse 2010-12-04T11:17:44+00:00 Will Deacon will.deacon@arm.com 2010-11-30T17:15:53+00:00 4d6b7a779be34e1df296abc1dc555134a8cf34af Russell reported a number of warnings coming from sparse when checking the ARM perf_event.c files: | perf_event.c seems to also have problems too: | | CHECK arch/arm/kernel/perf_event.c | arch/arm/kernel/perf_event.c:37:1: warning: symbol 'pmu_lock' was not declared. Should it be static? | arch/arm/kernel/perf_event.c:70:1: warning: symbol 'cpu_hw_events' was not declared. Should it be static? | arch/arm/kernel/perf_event.c:1006:1: warning: symbol 'armv6pmu_enable_event' was not declared. Should it be static? | arch/arm/kernel/perf_event.c:1113:1: warning: symbol 'armv6pmu_stop' was not declared. Should it be static? | arch/arm/kernel/perf_event.c:1956:6: warning: symbol 'armv7pmu_enable_event' was not declared. Should it be static? | arch/arm/kernel/perf_event.c:3072:14: warning: incorrect type in argument 1 (different address spaces) | arch/arm/kernel/perf_event.c:3072:14: expected void const volatile [noderef] <asn:1>*<noident> | arch/arm/kernel/perf_event.c:3072:14: got struct frame_tail *tail | arch/arm/kernel/perf_event.c:3074:49: warning: incorrect type in argument 2 (different address spaces) | arch/arm/kernel/perf_event.c:3074:49: expected void const [noderef] <asn:1>*from | arch/arm/kernel/perf_event.c:3074:49: got struct frame_tail *tail This patch resolves these issues so we can live in silence again. Reported-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
Russell reported a number of warnings coming from sparse when
checking the ARM perf_event.c files:

| perf_event.c seems to also have problems too:
|
|   CHECK   arch/arm/kernel/perf_event.c
|   arch/arm/kernel/perf_event.c:37:1: warning: symbol 'pmu_lock' was not declared. Should it be static?
|   arch/arm/kernel/perf_event.c:70:1: warning: symbol 'cpu_hw_events' was not declared. Should it be static?
|   arch/arm/kernel/perf_event.c:1006:1: warning: symbol 'armv6pmu_enable_event' was not declared. Should it be static?
|   arch/arm/kernel/perf_event.c:1113:1: warning: symbol 'armv6pmu_stop' was not declared. Should it be static?
|   arch/arm/kernel/perf_event.c:1956:6: warning: symbol 'armv7pmu_enable_event' was not declared. Should it be static?
|   arch/arm/kernel/perf_event.c:3072:14: warning: incorrect type in argument 1 (different address spaces)
|   arch/arm/kernel/perf_event.c:3072:14:    expected void const volatile [noderef] <asn:1>*<noident>
|   arch/arm/kernel/perf_event.c:3072:14:    got struct frame_tail *tail
|   arch/arm/kernel/perf_event.c:3074:49: warning: incorrect type in argument 2 (different address spaces)
|   arch/arm/kernel/perf_event.c:3074:49:    expected void const [noderef] <asn:1>*from
|   arch/arm/kernel/perf_event.c:3074:49:    got struct frame_tail *tail

This patch resolves these issues so we can live in silence
again.

Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: perf: separate PMU backends into multiple files 2010-11-25T16:52:08+00:00 Will Deacon will.deacon@arm.com 2010-11-13T19:04:32+00:00 43eab87828fee65f89f4088736b2b7a187390a2f The ARM perf_event.c file contains all PMU backends and, as new PMUs are introduced, will continue to grow. This patch follows the example of x86 and splits the PMU implementations into separate files which are then #included back into the main file. Compile-time guards are added to each PMU file to avoid compiling in code that is not relevant for the version of the architecture which we are targetting. Acked-by: Jean Pihet <j-pihet@ti.com> Signed-off-by: Will Deacon <will.deacon@arm.com> 
The ARM perf_event.c file contains all PMU backends and, as new PMUs
are introduced, will continue to grow.

This patch follows the example of x86 and splits the PMU implementations
into separate files which are then #included back into the main
file. Compile-time guards are added to each PMU file to avoid compiling
in code that is not relevant for the version of the architecture which
we are targetting.

Acked-by: Jean Pihet <j-pihet@ti.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>