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From: Andrew Morton on 28 Jul 2010 16:00 On Tue, 27 Jul 2010 22:29:39 +1200 Michael Cree <mcree(a)orcon.net.nz> wrote: > This implements hardware performance events for the EV67 and later > CPUs within the Linux performance events subsystem. Only using the > performance monitoring unit in HP/Compaq's so called "Aggregrate > mode" is supported. > > The code has been implemented in a manner that makes extension to > other older Alpha CPUs relatively straightforward should some mug > wish to indulge his or herself. Below is the incremental diff. I have a note here that Peter had issues with the earlier version of this patch. But I see no info here regarding what those issues were, nor whether or how they were addressed. arch/alpha/kernel/perf_event.c | 32 ++++++++++++++++++------------- arch/alpha/kernel/time.c | 26 +++++++++++++++++++++++++ 2 files changed, 45 insertions(+), 13 deletions(-) diff -puN arch/alpha/kernel/perf_event.c~a arch/alpha/kernel/perf_event.c --- a/arch/alpha/kernel/perf_event.c~a +++ a/arch/alpha/kernel/perf_event.c @@ -517,8 +517,10 @@ static void alpha_pmu_read(struct perf_e static void alpha_pmu_unthrottle(struct perf_event *event) { struct hw_perf_event *hwc = &event->hw; + struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); - wrperfmon(PERFMON_CMD_ENABLE, (1<<hwc->idx)); + cpuc->idx_mask |= 1UL<<hwc->idx; + wrperfmon(PERFMON_CMD_ENABLE, (1UL<<hwc->idx)); } @@ -756,12 +758,19 @@ static void alpha_perf_event_irq_handler __get_cpu_var(irq_pmi_count)++; cpuc = &__get_cpu_var(cpu_hw_events); - /* la_ptr is the counter that overflowed. */ + /* Completely counting through the PMC's period to trigger a new PMC + * overflow interrupt while in this interrupt routine is utterly + * disastrous! The EV6 and EV67 counters are sufficiently large to + * prevent this but to be really sure disable the PMCs. + */ + wrperfmon(PERFMON_CMD_DISABLE, cpuc->idx_mask); - if (la_ptr >= perf_max_events) { + /* la_ptr is the counter that overflowed. */ + if (unlikely(la_ptr >= perf_max_events)) { /* This should never occur! */ irq_err_count++; pr_warning("PMI: silly index %ld\n", la_ptr); + wrperfmon(PERFMON_CMD_ENABLE, cpuc->idx_mask); return; } @@ -773,17 +782,19 @@ static void alpha_perf_event_irq_handler break; } - if (j == cpuc->n_events) { + if (unlikely(j == cpuc->n_events)) { /* This can occur if the event is disabled right on a PMC overflow. */ + wrperfmon(PERFMON_CMD_ENABLE, cpuc->idx_mask); return; } event = cpuc->event[j]; - if (!event) { + if (unlikely(!event)) { /* This should never occur! */ irq_err_count++; pr_warning("PMI: No event at index %d!\n", idx); + wrperfmon(PERFMON_CMD_ENABLE, cpuc->idx_mask); return; } @@ -792,24 +803,19 @@ static void alpha_perf_event_irq_handler data.period = event->hw.last_period; if (alpha_perf_event_set_period(event, hwc, idx)) { - if (perf_event_overflow(event, 0, &data, regs)) { + if (perf_event_overflow(event, 1, &data, regs)) { /* Interrupts coming too quickly; "throttle" the * counter, i.e., disable it for a little while. */ - wrperfmon(PERFMON_CMD_DISABLE, 1<<idx); + cpuc->idx_mask &= ~(1UL<<idx); } } + wrperfmon(PERFMON_CMD_ENABLE, cpuc->idx_mask); return; } -/* I wonder what this is for ??? */ -void set_perf_event_pending(void) -{ -} - - /* * Init call to initialise performance events at kernel startup. diff -puN arch/alpha/kernel/time.c~a arch/alpha/kernel/time.c --- a/arch/alpha/kernel/time.c~a +++ a/arch/alpha/kernel/time.c @@ -41,6 +41,7 @@ #include <linux/init.h> #include <linux/bcd.h> #include <linux/profile.h> +#include <linux/perf_event.h> #include <asm/uaccess.h> #include <asm/io.h> @@ -82,6 +83,26 @@ static struct { unsigned long est_cycle_freq; +#ifdef CONFIG_PERF_EVENTS + +DEFINE_PER_CPU(u8, perf_event_pending); + +#define set_perf_event_pending_flag() __get_cpu_var(perf_event_pending) = 1 +#define test_perf_event_pending() __get_cpu_var(perf_event_pending) +#define clear_perf_event_pending() __get_cpu_var(perf_event_pending) = 0 + +void set_perf_event_pending(void) +{ + set_perf_event_pending_flag(); +} + +#else /* CONFIG_PERF_EVENTS */ + +#define test_perf_event_pending() 0 +#define clear_perf_event_pending() + +#endif /* CONFIG_PERF_EVENTS */ + static inline __u32 rpcc(void) { @@ -175,6 +196,11 @@ irqreturn_t timer_interrupt(int irq, voi update_process_times(user_mode(get_irq_regs())); #endif + if (test_perf_event_pending()) { + clear_perf_event_pending(); + perf_event_do_pending(); + } + return IRQ_HANDLED; } _ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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