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Date: Mon, 23 Mar 2009 20:57:16 GMT
From: Peter Zijlstra <a.p.zijlstra@...llo.nl>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, paulus@...ba.org, hpa@...or.com,
mingo@...hat.com, a.p.zijlstra@...llo.nl, tglx@...utronix.de,
fengguang.wu@...el.com, mingo@...e.hu
Subject: [tip:perfcounters/core] kerneltop: use mmap() output
Commit-ID: 0488f729768605502accdae7335911b4400a5927
Gitweb: http://git.kernel.org/tip/0488f729768605502accdae7335911b4400a5927
Author: Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Mon, 23 Mar 2009 18:22:12 +0100
Committer: Ingo Molnar <mingo@...e.hu>
CommitDate: Mon, 23 Mar 2009 21:45:11 +0100
kerneltop: use mmap() output
update kerneltop to use the mmap() output to gather overflow information
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Wu Fengguang <fengguang.wu@...el.com>
Cc: Paul Mackerras <paulus@...ba.org>
LKML-Reference: <20090323172417.677932499@...llo.nl>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
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 a72c9bd..80b7905 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) {
--
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