From 716c69fecacd42f2a304a97158e04af2786a3f65 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 7 Jun 2009 17:31:52 +0200 Subject: perf top: Fall back to cpu-clock-tick hrtimer sampling if no cycle counter available On architectures/CPUs without PMU support but with perfcounters enabled 'perf top' currently fails because it cannot create a cycle based hw-perfcounter. Fall back to the cpu-clock-tick sw-perfcounter in this case, which is hrtimer based and will always work (as long as perfcounters is enabled). Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo LKML-Reference: Signed-off-by: Ingo Molnar --- tools/perf/builtin-top.c | 113 ++++++++++++++++++++++++++++------------------- 1 file changed, 68 insertions(+), 45 deletions(-) (limited to 'tools/perf/builtin-top.c') diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c index fdc1d5863b0..6da30a140e8 100644 --- a/tools/perf/builtin-top.c +++ b/tools/perf/builtin-top.c @@ -527,58 +527,81 @@ static void mmap_read(void) } } -static int __cmd_top(void) +int nr_poll; +int group_fd; + +static void start_counter(int i, int counter) { struct perf_counter_attr *attr; - pthread_t thread; - int i, counter, group_fd, nr_poll = 0; unsigned int cpu; + + cpu = profile_cpu; + if (target_pid == -1 && profile_cpu == -1) + cpu = i; + + attr = attrs + counter; + + attr->sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_TID; + attr->freq = freq; + +try_again: + fd[i][counter] = sys_perf_counter_open(attr, target_pid, cpu, group_fd, 0); + + if (fd[i][counter] < 0) { + int err = errno; + + error("sys_perf_counter_open() syscall returned with %d (%s)\n", + fd[i][counter], strerror(err)); + + if (err == EPERM) + die(" No permission - are you root?\n"); + /* + * If it's cycles then fall back to hrtimer + * based cpu-clock-tick sw counter, which + * is always available even if no PMU support: + */ + if (attr->type == PERF_TYPE_HARDWARE + && attr->config == PERF_COUNT_CPU_CYCLES) { + + warning(" ... trying to fall back to cpu-clock-ticks\n"); + attr->type = PERF_TYPE_SOFTWARE; + attr->config = PERF_COUNT_CPU_CLOCK; + goto try_again; + } + exit(-1); + } + assert(fd[i][counter] >= 0); + fcntl(fd[i][counter], F_SETFL, O_NONBLOCK); + + /* + * First counter acts as the group leader: + */ + if (group && group_fd == -1) + group_fd = fd[i][counter]; + + event_array[nr_poll].fd = fd[i][counter]; + event_array[nr_poll].events = POLLIN; + nr_poll++; + + mmap_array[i][counter].counter = counter; + mmap_array[i][counter].prev = 0; + mmap_array[i][counter].mask = mmap_pages*page_size - 1; + mmap_array[i][counter].base = mmap(NULL, (mmap_pages+1)*page_size, + PROT_READ, MAP_SHARED, fd[i][counter], 0); + if (mmap_array[i][counter].base == MAP_FAILED) + die("failed to mmap with %d (%s)\n", errno, strerror(errno)); +} + +static int __cmd_top(void) +{ + pthread_t thread; + int i, counter; int ret; for (i = 0; i < nr_cpus; i++) { group_fd = -1; - for (counter = 0; counter < nr_counters; counter++) { - - cpu = profile_cpu; - if (target_pid == -1 && profile_cpu == -1) - cpu = i; - - attr = attrs + counter; - - attr->sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_TID; - attr->freq = freq; - - fd[i][counter] = sys_perf_counter_open(attr, target_pid, cpu, group_fd, 0); - if (fd[i][counter] < 0) { - int err = errno; - - error("syscall returned with %d (%s)\n", - fd[i][counter], strerror(err)); - if (err == EPERM) - printf("Are you root?\n"); - exit(-1); - } - assert(fd[i][counter] >= 0); - fcntl(fd[i][counter], F_SETFL, O_NONBLOCK); - - /* - * First counter acts as the group leader: - */ - if (group && group_fd == -1) - group_fd = fd[i][counter]; - - event_array[nr_poll].fd = fd[i][counter]; - event_array[nr_poll].events = POLLIN; - nr_poll++; - - mmap_array[i][counter].counter = counter; - mmap_array[i][counter].prev = 0; - mmap_array[i][counter].mask = mmap_pages*page_size - 1; - mmap_array[i][counter].base = mmap(NULL, (mmap_pages+1)*page_size, - PROT_READ, MAP_SHARED, fd[i][counter], 0); - if (mmap_array[i][counter].base == MAP_FAILED) - die("failed to mmap with %d (%s)\n", errno, strerror(errno)); - } + for (counter = 0; counter < nr_counters; counter++) + start_counter(i, counter); } /* Wait for a minimal set of events before starting the snapshot */ -- cgit v1.2.3