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ARCv2: perf: Support sampling events using overflow interrupts

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In times of ARC 700 performance counters didn't have support of
interrupt an so for ARC we only had support of non-sampling events.

Put simply only "perf stat" was functional.

Now with ARC HS we have support of interrupts in performance counters
which this change introduces support of.

ARC performance counters act in the following way in regard of
interrupts generation.
 [1] A counter counts starting from value set in PCT_COUNT register pair
 [2] Once counter reaches value set in PCT_INT_CNT interrupt is raised

Basic setup look like this:
 [1] PCT_COUNT = 0;
 [2] PCT_INT_CNT = __limit_value__;
 [3] Enable interrupts for that counter and let it run
 [4] Let counter reach its limit
 [5] Handle interrupt when it happens

Note that PCT HW block is build in CPU core and so ints interrupt
line (which is basically OR of all counters IRQs) is wired directly to
top-level IRQC. That means do de-assert PCT interrupt it's required to
reset IRQs from all counters that have reached their limit values.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Alexey Brodkin
2015-08-24 13:48:06 +03:00
committed by Vineet Gupta
parent 1fe8bfa5ff
commit 36481cf7fb
2 changed files with 126 additions and 10 deletions
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8
arch/arc/include/asm/perf_event.h
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@@ -29,15 +29,19 @@
#define ARC_REG_PCT_CONFIG 0x254
#define ARC_REG_PCT_CONTROL 0x255
#define ARC_REG_PCT_INDEX 0x256
#define ARC_REG_PCT_INT_CNTL 0x25C
#define ARC_REG_PCT_INT_CNTH 0x25D
#define ARC_REG_PCT_INT_CTRL 0x25E
#define ARC_REG_PCT_INT_ACT 0x25F
#define ARC_REG_PCT_CONTROL_CC (1 << 16) /* clear counts */
#define ARC_REG_PCT_CONTROL_SN (1 << 17) /* snapshot */
struct arc_reg_pct_build {
#ifdef CONFIG_CPU_BIG_ENDIAN
unsigned int m:8, c:8, r:6, s:2, v:8;
unsigned int m:8, c:8, r:5, i:1, s:2, v:8;
#else
unsigned int v:8, s:2, r:6, c:8, m:8;
unsigned int v:8, s:2, i:1, r:5, c:8, m:8;
#endif
};