Adding sysfs 'precise' attribute for cpu device (/sys/devices/cpu/precise) to show the maximum value for perf event precise attribute.
This will be initially used for automated precise event perf test and could be helpful otherwise. TODO Arnaldo suggested to use this as a guide for default adding of precise attribute for HW events. Signed-off-by: Jiri Olsa <[email protected]> Cc: Corey Ashford <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Andi Kleen <[email protected]> Cc: David Ahern <[email protected]> --- arch/x86/kernel/cpu/perf_event.c | 34 +++++++++++++++++++++++++--------- 1 file changed, 25 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 6774c17..190995e 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -377,19 +377,26 @@ static inline int precise_br_compat(struct perf_event *event) return m == b; } -int x86_pmu_hw_config(struct perf_event *event) +static int x86_get_precise(void) { - if (event->attr.precise_ip) { - int precise = 0; + int precise = 0; - /* Support for constant skid */ - if (x86_pmu.pebs_active && !x86_pmu.pebs_broken) { + /* Support for constant skid */ + if (x86_pmu.pebs_active && !x86_pmu.pebs_broken) { + precise++; + + /* Support for IP fixup */ + if (x86_pmu.lbr_nr) precise++; + } - /* Support for IP fixup */ - if (x86_pmu.lbr_nr) - precise++; - } + return precise; +} + +int x86_pmu_hw_config(struct perf_event *event) +{ + if (event->attr.precise_ip) { + int precise = x86_get_precise(); if (event->attr.precise_ip > precise) return -EOPNOTSUPP; @@ -1700,6 +1707,13 @@ static int x86_pmu_event_init(struct perf_event *event) return err; } +static ssize_t get_attr_precise(struct device *cdev, + struct device_attribute *attr, + char *buf) +{ + return snprintf(buf, 10, "%d\n", x86_get_precise()); +} + static int x86_pmu_event_idx(struct perf_event *event) { int idx = event->hw.idx; @@ -1752,9 +1766,11 @@ static ssize_t set_attr_rdpmc(struct device *cdev, } static DEVICE_ATTR(rdpmc, S_IRUSR | S_IWUSR, get_attr_rdpmc, set_attr_rdpmc); +static DEVICE_ATTR(precise, S_IRUGO, get_attr_precise, NULL); static struct attribute *x86_pmu_attrs[] = { &dev_attr_rdpmc.attr, + &dev_attr_precise.attr, NULL, }; -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
