diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/perf_counter/kerneltop.c | 93 |
1 files changed, 79 insertions, 14 deletions
diff --git a/Documentation/perf_counter/kerneltop.c b/Documentation/perf_counter/kerneltop.c index a72c9bd28071..80b790553ec8 100644 --- a/Documentation/perf_counter/kerneltop.c +++ b/Documentation/perf_counter/kerneltop.c @@ -84,6 +84,7 @@ #include <sys/prctl.h> #include <sys/wait.h> #include <sys/uio.h> +#include <sys/mman.h> #include <linux/unistd.h> @@ -119,17 +120,25 @@ typedef long long __s64; #ifdef __x86_64__ -# define __NR_perf_counter_open 295 +#define __NR_perf_counter_open 295 +#define rmb() asm volatile("lfence" ::: "memory") +#define cpu_relax() asm volatile("rep; nop" ::: "memory"); #endif #ifdef __i386__ -# define __NR_perf_counter_open 333 +#define __NR_perf_counter_open 333 +#define rmb() asm volatile("lfence" ::: "memory") +#define cpu_relax() asm volatile("rep; nop" ::: "memory"); #endif #ifdef __powerpc__ #define __NR_perf_counter_open 319 +#define rmb() asm volatile ("sync" ::: "memory") +#define cpu_relax() asm volatile ("" ::: "memory"); #endif +#define unlikely(x) __builtin_expect(!!(x), 0) + asmlinkage int sys_perf_counter_open( struct perf_counter_hw_event *hw_event_uptr __user, pid_t pid, @@ -181,6 +190,7 @@ static int profile_cpu = -1; static int nr_cpus = 0; static int nmi = 1; static int group = 0; +static unsigned int page_size; static char *vmlinux; @@ -1117,16 +1127,68 @@ static void process_options(int argc, char *argv[]) } } +struct mmap_data { + int counter; + void *base; + unsigned int mask; + unsigned int prev; +}; + +static unsigned int mmap_read_head(struct mmap_data *md) +{ + struct perf_counter_mmap_page *pc = md->base; + unsigned int seq, head; + +repeat: + rmb(); + seq = pc->lock; + + if (unlikely(seq & 1)) { + cpu_relax(); + goto repeat; + } + + head = pc->data_head; + + rmb(); + if (pc->lock != seq) + goto repeat; + + return head; +} + +static void mmap_read(struct mmap_data *md) +{ + unsigned int head = mmap_read_head(md); + unsigned int old = md->prev; + unsigned char *data = md->base + page_size; + + if (head - old > md->mask) { + printf("ERROR: failed to keep up with mmap data\n"); + exit(-1); + } + + for (; old != head;) { + __u64 *ptr = (__u64 *)&data[old & md->mask]; + old += sizeof(__u64); + + process_event(*ptr, md->counter); + } + + md->prev = old; +} + int main(int argc, char *argv[]) { struct pollfd event_array[MAX_NR_CPUS][MAX_COUNTERS]; + struct mmap_data mmap_array[MAX_NR_CPUS][MAX_COUNTERS]; struct perf_counter_hw_event hw_event; int i, counter, group_fd; unsigned int cpu; - uint64_t ip; - ssize_t res; int ret; + page_size = sysconf(_SC_PAGE_SIZE); + process_options(argc, argv); nr_cpus = sysconf(_SC_NPROCESSORS_ONLN); @@ -1153,8 +1215,6 @@ int main(int argc, char *argv[]) hw_event.record_type = PERF_RECORD_IRQ; hw_event.nmi = nmi; - printf("FOO: %d %llx %llx\n", counter, event_id[counter], event_count[counter]); - fd[i][counter] = sys_perf_counter_open(&hw_event, tid, cpu, group_fd, 0); fcntl(fd[i][counter], F_SETFL, O_NONBLOCK); if (fd[i][counter] < 0) { @@ -1174,6 +1234,17 @@ int main(int argc, char *argv[]) event_array[i][counter].fd = fd[i][counter]; event_array[i][counter].events = POLLIN; + + mmap_array[i][counter].counter = counter; + mmap_array[i][counter].prev = 0; + mmap_array[i][counter].mask = 2*page_size - 1; + mmap_array[i][counter].base = mmap(NULL, 3*page_size, + PROT_READ, MAP_SHARED, fd[i][counter], 0); + if (mmap_array[i][counter].base == MAP_FAILED) { + printf("kerneltop error: failed to mmap with %d (%s)\n", + errno, strerror(errno)); + exit(-1); + } } } @@ -1188,14 +1259,8 @@ int main(int argc, char *argv[]) int hits = events; for (i = 0; i < nr_cpus; i++) { - for (counter = 0; counter < nr_counters; counter++) { - res = read(fd[i][counter], (char *) &ip, sizeof(ip)); - if (res > 0) { - assert(res == sizeof(ip)); - - process_event(ip, counter); - } - } + for (counter = 0; counter < nr_counters; counter++) + mmap_read(&mmap_array[i][counter]); } if (time(NULL) >= last_refresh + delay_secs) { |