Teach kerneltop about the new output ABI.
XXX: anybody fancy integrating the PID/TID data into the output?
Bump the mmap_data pages a little because we bloated the output and
have to be more careful about overruns with structured data.
Signed-off-by: Peter Zijlstra <[email protected]>
---
Documentation/perf_counter/kerneltop.c | 65 +++++++++++++++++++++++++++++----
1 file changed, 59 insertions(+), 6 deletions(-)
Index: linux-2.6/Documentation/perf_counter/kerneltop.c
===================================================================
--- linux-2.6.orig/Documentation/perf_counter/kerneltop.c
+++ linux-2.6/Documentation/perf_counter/kerneltop.c
@@ -134,6 +134,11 @@
#endif
#define unlikely(x) __builtin_expect(!!(x), 0)
+#define min(x, y) ({ \
+ typeof(x) _min1 = (x); \
+ typeof(y) _min2 = (y); \
+ (void) (&_min1 == &_min2); \
+ _min1 < _min2 ? _min1 : _min2; })
asmlinkage int sys_perf_counter_open(
struct perf_counter_hw_event *hw_event_uptr __user,
@@ -178,7 +183,7 @@ static int nr_cpus = 0;
static int nmi = 1;
static int group = 0;
static unsigned int page_size;
-static unsigned int mmap_pages = 4;
+static unsigned int mmap_pages = 16;
static char *vmlinux;
@@ -1147,28 +1152,75 @@ static void mmap_read(struct mmap_data *
unsigned int head = mmap_read_head(md);
unsigned int old = md->prev;
unsigned char *data = md->base + page_size;
+ int diff;
gettimeofday(&this_read, NULL);
- if (head - old > md->mask) {
+ /*
+ * If we're further behind than half the buffer, there's a chance
+ * the writer will bite our tail and screw up the events under us.
+ *
+ * If we somehow ended up ahead of the head, we got messed up.
+ *
+ * In either case, truncate and restart at head.
+ */
+ diff = head - old;
+ if (diff > md->mask / 2 || diff < 0) {
struct timeval iv;
unsigned long msecs;
timersub(&this_read, &last_read, &iv);
msecs = iv.tv_sec*1000 + iv.tv_usec/1000;
- fprintf(stderr, "WARNING: failed to keep up with mmap data. Last read %lu msecs ago.\n", msecs);
+ fprintf(stderr, "WARNING: failed to keep up with mmap data."
+ " Last read %lu msecs ago.\n", msecs);
+ /*
+ * head points to a known good entry, start there.
+ */
old = head;
}
last_read = this_read;
for (; old != head;) {
- __u64 *ptr = (__u64 *)&data[old & md->mask];
- old += sizeof(__u64);
+ struct event_struct {
+ struct perf_event_header header;
+ __u64 ip;
+ __u32 pid, tid;
+ } *event = (struct event_struct *)&data[old & md->mask];
+ struct event_struct event_copy;
+
+ unsigned int size = event->header.size;
- process_event(*ptr, md->counter);
+ /*
+ * Event straddles the mmap boundary -- header should always
+ * be inside due to u64 alignment of output.
+ */
+ if ((old & md->mask) + size != ((old + size) & md->mask)) {
+ unsigned int offset = old;
+ unsigned int len = sizeof(*event), cpy;
+ void *dst = &event_copy;
+
+ do {
+ cpy = min(md->mask + 1 - (offset & md->mask), len);
+ memcpy(dst, &data[offset & md->mask], cpy);
+ offset += cpy;
+ dst += cpy;
+ len -= cpy;
+ } while (len);
+
+ event = &event_copy;
+ }
+
+ old += size;
+
+ switch (event->header.type) {
+ case PERF_EVENT_IP:
+ case PERF_EVENT_IP | __PERF_EVENT_TID:
+ process_event(event->ip, md->counter);
+ break;
+ }
}
md->prev = old;
@@ -1214,6 +1266,7 @@ int main(int argc, char *argv[])
hw_event.irq_period = event_count[counter];
hw_event.record_type = PERF_RECORD_IRQ;
hw_event.nmi = nmi;
+ hw_event.include_tid = 1;
fd[i][counter] = sys_perf_counter_open(&hw_event, tid, cpu, group_fd, 0);
if (fd[i][counter] < 0) {
--
Commit-ID: ee8ff2070444f88524ef89555e3996c8be44170d
Gitweb: http://git.kernel.org/tip/ee8ff2070444f88524ef89555e3996c8be44170d
Author: Peter Zijlstra <[email protected]>
AuthorDate: Wed, 25 Mar 2009 12:30:27 +0100
Committer: Ingo Molnar <[email protected]>
CommitDate: Wed, 25 Mar 2009 13:02:53 +0100
perf_counter: kerneltop: output event support
Teach kerneltop about the new output ABI.
XXX: anybody fancy integrating the PID/TID data into the output?
Bump the mmap_data pages a little because we bloated the output and
have to be more careful about overruns with structured data.
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Wu Fengguang <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
---
Documentation/perf_counter/kerneltop.c | 65 +++++++++++++++++++++++++++++---
1 files changed, 59 insertions(+), 6 deletions(-)
diff --git a/Documentation/perf_counter/kerneltop.c b/Documentation/perf_counter/kerneltop.c
index 3e45bf6..fda1438 100644
--- a/Documentation/perf_counter/kerneltop.c
+++ b/Documentation/perf_counter/kerneltop.c
@@ -134,6 +134,11 @@
#endif
#define unlikely(x) __builtin_expect(!!(x), 0)
+#define min(x, y) ({ \
+ typeof(x) _min1 = (x); \
+ typeof(y) _min2 = (y); \
+ (void) (&_min1 == &_min2); \
+ _min1 < _min2 ? _min1 : _min2; })
asmlinkage int sys_perf_counter_open(
struct perf_counter_hw_event *hw_event_uptr __user,
@@ -178,7 +183,7 @@ static int nr_cpus = 0;
static int nmi = 1;
static int group = 0;
static unsigned int page_size;
-static unsigned int mmap_pages = 4;
+static unsigned int mmap_pages = 16;
static char *vmlinux;
@@ -1147,28 +1152,75 @@ 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;
+ int diff;
gettimeofday(&this_read, NULL);
- if (head - old > md->mask) {
+ /*
+ * If we're further behind than half the buffer, there's a chance
+ * the writer will bite our tail and screw up the events under us.
+ *
+ * If we somehow ended up ahead of the head, we got messed up.
+ *
+ * In either case, truncate and restart at head.
+ */
+ diff = head - old;
+ if (diff > md->mask / 2 || diff < 0) {
struct timeval iv;
unsigned long msecs;
timersub(&this_read, &last_read, &iv);
msecs = iv.tv_sec*1000 + iv.tv_usec/1000;
- fprintf(stderr, "WARNING: failed to keep up with mmap data. Last read %lu msecs ago.\n", msecs);
+ fprintf(stderr, "WARNING: failed to keep up with mmap data."
+ " Last read %lu msecs ago.\n", msecs);
+ /*
+ * head points to a known good entry, start there.
+ */
old = head;
}
last_read = this_read;
for (; old != head;) {
- __u64 *ptr = (__u64 *)&data[old & md->mask];
- old += sizeof(__u64);
+ struct event_struct {
+ struct perf_event_header header;
+ __u64 ip;
+ __u32 pid, tid;
+ } *event = (struct event_struct *)&data[old & md->mask];
+ struct event_struct event_copy;
+
+ unsigned int size = event->header.size;
+
+ /*
+ * Event straddles the mmap boundary -- header should always
+ * be inside due to u64 alignment of output.
+ */
+ if ((old & md->mask) + size != ((old + size) & md->mask)) {
+ unsigned int offset = old;
+ unsigned int len = sizeof(*event), cpy;
+ void *dst = &event_copy;
+
+ do {
+ cpy = min(md->mask + 1 - (offset & md->mask), len);
+ memcpy(dst, &data[offset & md->mask], cpy);
+ offset += cpy;
+ dst += cpy;
+ len -= cpy;
+ } while (len);
+
+ event = &event_copy;
+ }
- process_event(*ptr, md->counter);
+ old += size;
+
+ switch (event->header.type) {
+ case PERF_EVENT_IP:
+ case PERF_EVENT_IP | __PERF_EVENT_TID:
+ process_event(event->ip, md->counter);
+ break;
+ }
}
md->prev = old;
@@ -1214,6 +1266,7 @@ int main(int argc, char *argv[])
hw_event.irq_period = event_count[counter];
hw_event.record_type = PERF_RECORD_IRQ;
hw_event.nmi = nmi;
+ hw_event.include_tid = 1;
fd[i][counter] = sys_perf_counter_open(&hw_event, tid, cpu, group_fd, 0);
if (fd[i][counter] < 0) {
As I was stealing code from kerneltop today to use in the PAPI profiling
implementation, I ran across the code below:
Peter Zijlstra wrote:
> Teach kerneltop about the new output ABI.
>
> XXX: anybody fancy integrating the PID/TID data into the output?
>
> Bump the mmap_data pages a little because we bloated the output and
> have to be more careful about overruns with structured data.
>
> Signed-off-by: Peter Zijlstra <[email protected]>
> ---
[snip]
>
> @@ -1147,28 +1152,75 @@ static void mmap_read(struct mmap_data *
> unsigned int head = mmap_read_head(md);
> unsigned int old = md->prev;
> unsigned char *data = md->base + page_size;
> + int diff;
>
> gettimeofday(&this_read, NULL);
>
> - if (head - old > md->mask) {
> + /*
> + * If we're further behind than half the buffer, there's a chance
> + * the writer will bite our tail and screw up the events under us.
> + *
> + * If we somehow ended up ahead of the head, we got messed up.
> + *
> + * In either case, truncate and restart at head.
> + */
> + diff = head - old;
> + if (diff > md->mask / 2 || diff < 0) {
> struct timeval iv;
> unsigned long msecs;
>
> timersub(&this_read, &last_read, &iv);
> msecs = iv.tv_sec*1000 + iv.tv_usec/1000;
>
> - fprintf(stderr, "WARNING: failed to keep up with mmap data. Last read %lu msecs ago.\n", msecs);
> + fprintf(stderr, "WARNING: failed to keep up with mmap data."
> + " Last read %lu msecs ago.\n", msecs);
>
[snip]
The test for diff < 0 looks incorrect to me. This shouldn't be an
error, because it will frequently be the case that the head has wrapped
around back to the beginning of the mmap'd pages, while old is near the end.
What it needs to find out, I think, is if the modulo distance between
old and head is greater than 1/2 of the span of the mmap'd pages.
Here's a suggested change:
- diff = head - old;
+ diff = (head - old) & md->mask;
- if (diff > md->mask / 2 || diff < 0) {
+ if (diff > md->mask / 2) {
What do you think?
- Corey
On Fri, 2009-04-03 at 17:21 -0700, Corey Ashford wrote:
> As I was stealing code from kerneltop today to use in the PAPI profiling
> implementation, I ran across the code below:
>
> Peter Zijlstra wrote:
> > Teach kerneltop about the new output ABI.
> >
> > XXX: anybody fancy integrating the PID/TID data into the output?
> >
> > Bump the mmap_data pages a little because we bloated the output and
> > have to be more careful about overruns with structured data.
> >
> > Signed-off-by: Peter Zijlstra <[email protected]>
> > ---
> [snip]
>
> >
> > @@ -1147,28 +1152,75 @@ static void mmap_read(struct mmap_data *
> > unsigned int head = mmap_read_head(md);
> > unsigned int old = md->prev;
> > unsigned char *data = md->base + page_size;
> > + int diff;
> >
> > gettimeofday(&this_read, NULL);
> >
> > - if (head - old > md->mask) {
> > + /*
> > + * If we're further behind than half the buffer, there's a chance
> > + * the writer will bite our tail and screw up the events under us.
> > + *
> > + * If we somehow ended up ahead of the head, we got messed up.
> > + *
> > + * In either case, truncate and restart at head.
> > + */
> > + diff = head - old;
> > + if (diff > md->mask / 2 || diff < 0) {
> > struct timeval iv;
> > unsigned long msecs;
> >
> > timersub(&this_read, &last_read, &iv);
> > msecs = iv.tv_sec*1000 + iv.tv_usec/1000;
> >
> > - fprintf(stderr, "WARNING: failed to keep up with mmap data. Last read %lu msecs ago.\n", msecs);
> > + fprintf(stderr, "WARNING: failed to keep up with mmap data."
> > + " Last read %lu msecs ago.\n", msecs);
> >
> [snip]
>
> The test for diff < 0 looks incorrect to me. This shouldn't be an
> error, because it will frequently be the case that the head has wrapped
> around back to the beginning of the mmap'd pages, while old is near the end.
>
> What it needs to find out, I think, is if the modulo distance between
> old and head is greater than 1/2 of the span of the mmap'd pages.
> Here's a suggested change:
>
> - diff = head - old;
> + diff = (head - old) & md->mask;
> - if (diff > md->mask / 2 || diff < 0) {
> + if (diff > md->mask / 2) {
>
>
> What do you think?
head and old are both u32 and are monotonically incremented, that means
that (s32)(head - old) < 0 will only be true if old is ahead (or more
than 2^31 behind) of head.
Since mask will be smaller than 2^31 this seemed like a reasonable
integrity test.
Peter Zijlstra wrote:
> On Fri, 2009-04-03 at 17:21 -0700, Corey Ashford wrote:
>> As I was stealing code from kerneltop today to use in the PAPI profiling
>> implementation, I ran across the code below:
>>
>> Peter Zijlstra wrote:
>>> Teach kerneltop about the new output ABI.
>>>
>>> XXX: anybody fancy integrating the PID/TID data into the output?
>>>
>>> Bump the mmap_data pages a little because we bloated the output and
>>> have to be more careful about overruns with structured data.
>>>
>>> Signed-off-by: Peter Zijlstra <[email protected]>
>>> ---
>> [snip]
>>
>>> @@ -1147,28 +1152,75 @@ static void mmap_read(struct mmap_data *
>>> unsigned int head = mmap_read_head(md);
>>> unsigned int old = md->prev;
>>> unsigned char *data = md->base + page_size;
>>> + int diff;
>>>
>>> gettimeofday(&this_read, NULL);
>>>
>>> - if (head - old > md->mask) {
>>> + /*
>>> + * If we're further behind than half the buffer, there's a chance
>>> + * the writer will bite our tail and screw up the events under us.
>>> + *
>>> + * If we somehow ended up ahead of the head, we got messed up.
>>> + *
>>> + * In either case, truncate and restart at head.
>>> + */
>>> + diff = head - old;
>>> + if (diff > md->mask / 2 || diff < 0) {
>>> struct timeval iv;
>>> unsigned long msecs;
>>>
>>> timersub(&this_read, &last_read, &iv);
>>> msecs = iv.tv_sec*1000 + iv.tv_usec/1000;
>>>
>>> - fprintf(stderr, "WARNING: failed to keep up with mmap data. Last read %lu msecs ago.\n", msecs);
>>> + fprintf(stderr, "WARNING: failed to keep up with mmap data."
>>> + " Last read %lu msecs ago.\n", msecs);
>>>
>> [snip]
>>
>> The test for diff < 0 looks incorrect to me. This shouldn't be an
>> error, because it will frequently be the case that the head has wrapped
>> around back to the beginning of the mmap'd pages, while old is near the end.
>>
>> What it needs to find out, I think, is if the modulo distance between
>> old and head is greater than 1/2 of the span of the mmap'd pages.
>> Here's a suggested change:
>>
>> - diff = head - old;
>> + diff = (head - old) & md->mask;
>> - if (diff > md->mask / 2 || diff < 0) {
>> + if (diff > md->mask / 2) {
>>
>>
>> What do you think?
>
> head and old are both u32 and are monotonically incremented, that means
> that (s32)(head - old) < 0 will only be true if old is ahead (or more
> than 2^31 behind) of head.
>
> Since mask will be smaller than 2^31 this seemed like a reasonable
> integrity test.
Ah, I see. I assumed (but did not check) that there was logic to wrap
the old and head back to the beginning when they hit the end of the
mmap'd pages.
Thanks for your reply.
- Corey