csky pmu counter may have different io width. When the counter is smaller
then 64 bits and counter value is smaller than the old value, it will
result to a extremely large delta value. So the sampled value should be
extend to 64 bits to avoid this, the extension bits base on the
reg-io-width property from dts.
Signed-off-by: Mao Han <[email protected]>
CC: Guo Ren <[email protected]>
CC: [email protected]
---
arch/csky/kernel/perf_event.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/arch/csky/kernel/perf_event.c b/arch/csky/kernel/perf_event.c
index c022acc..f1b3cdf 100644
--- a/arch/csky/kernel/perf_event.c
+++ b/arch/csky/kernel/perf_event.c
@@ -18,6 +18,7 @@ static void (*hw_raw_write_mapping[CSKY_PMU_MAX_EVENTS])(uint64_t val);
struct csky_pmu_t {
struct pmu pmu;
+ uint32_t sign_extend;
uint32_t hpcr;
} csky_pmu;
@@ -806,7 +807,13 @@ static void csky_perf_event_update(struct perf_event *event,
struct hw_perf_event *hwc)
{
uint64_t prev_raw_count = local64_read(&hwc->prev_count);
- uint64_t new_raw_count = hw_raw_read_mapping[hwc->idx]();
+ /*
+ * Extend count value to 64bit, otherwise delta calculation would
+ * be incorrect when overflow occurs.
+ */
+ uint64_t new_raw_count = ((int64_t)hw_raw_read_mapping[hwc->idx]()
+ << csky_pmu.sign_extend)
+ >> csky_pmu.sign_extend;
int64_t delta = new_raw_count - prev_raw_count;
/*
@@ -1037,6 +1044,7 @@ int csky_pmu_device_probe(struct platform_device *pdev,
const struct of_device_id *of_id;
csky_pmu_init init_fn;
struct device_node *node = pdev->dev.of_node;
+ int cnt_width;
int ret = -ENODEV;
of_id = of_match_node(of_table, pdev->dev.of_node);
@@ -1045,6 +1053,12 @@ int csky_pmu_device_probe(struct platform_device *pdev,
ret = init_fn(&csky_pmu);
}
+ if (!of_property_read_u32(node, "reg-io-width", &cnt_width)) {
+ csky_pmu.sign_extend = 64 - cnt_width;
+ } else {
+ csky_pmu.sign_extend = 16;
+ }
+
if (ret) {
pr_notice("[perf] failed to probe PMU!\n");
return ret;
--
2.7.4
Hello Mao,
Title Correct: csky: Add reg-io-width property for csky pmu
It's not a reg-io-width. I think it's a count-width, isn't it?
On Mon, Jun 3, 2019 at 2:47 PM Mao Han <[email protected]> wrote:
>
> csky pmu counter may have different io width. When the counter is smaller
Csky pmu counter ..., capitalize the first letter.
> then 64 bits and counter value is smaller than the old value, it will
> result to a extremely large delta value. So the sampled value should be
> extend to 64 bits to avoid this, the extension bits base on the
> reg-io-width property from dts.
>
> Signed-off-by: Mao Han <[email protected]>
> CC: Guo Ren <[email protected]>
Please correct to "Cc:"
> CC: [email protected]
Remove it and don't add mailing list in commit msg, Cc means you want
who to pick up the patch.
> ---
> arch/csky/kernel/perf_event.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/arch/csky/kernel/perf_event.c b/arch/csky/kernel/perf_event.c
> index c022acc..f1b3cdf 100644
> --- a/arch/csky/kernel/perf_event.c
> +++ b/arch/csky/kernel/perf_event.c
> @@ -18,6 +18,7 @@ static void (*hw_raw_write_mapping[CSKY_PMU_MAX_EVENTS])(uint64_t val);
>
> struct csky_pmu_t {
> struct pmu pmu;
> + uint32_t sign_extend;
Please use count_width here.
> uint32_t hpcr;
> } csky_pmu;
>
> @@ -806,7 +807,13 @@ static void csky_perf_event_update(struct perf_event *event,
> struct hw_perf_event *hwc)
> {
> uint64_t prev_raw_count = local64_read(&hwc->prev_count);
> - uint64_t new_raw_count = hw_raw_read_mapping[hwc->idx]();
> + /*
> + * Extend count value to 64bit, otherwise delta calculation would
Sign extend count value to 64bit, ...
> + * be incorrect when overflow occurs.
> + */
> + uint64_t new_raw_count = ((int64_t)hw_raw_read_mapping[hwc->idx]()
> + << csky_pmu.sign_extend)
> + >> csky_pmu.sign_extend;
Please use sign_extend64 in bitops.h.
+ uint64_t new_raw_count = ((int64_t)hw_raw_read_mapping[hwc->idx]()
+ << 64 - csky_pmu.count_width)
+ >> 64 - csky_pmu.count_width;
> int64_t delta = new_raw_count - prev_raw_count;
>
> /*
> @@ -1037,6 +1044,7 @@ int csky_pmu_device_probe(struct platform_device *pdev,
> const struct of_device_id *of_id;
> csky_pmu_init init_fn;
> struct device_node *node = pdev->dev.of_node;
> + int cnt_width;
Please remove.
> int ret = -ENODEV;
>
> of_id = of_match_node(of_table, pdev->dev.of_node);
> @@ -1045,6 +1053,12 @@ int csky_pmu_device_probe(struct platform_device *pdev,
> ret = init_fn(&csky_pmu);
> }
>
> + if (!of_property_read_u32(node, "reg-io-width", &cnt_width)) {
> + csky_pmu.sign_extend = 64 - cnt_width;
63?
Please use count_width, see above.
> + } else {
> + csky_pmu.sign_extend = 16;
Please define a macro for define DEFAULT_COUNT_WIDTH 48 and change the
format like this:
if (of_property_read_u32(node, "count-width", &csky_pmu.count_width))
csky_pmu.count_width = DEFAULT_COUNT_WIDTH;
Best Regards
Guo Ren