diff options
author | Daniel Bristot de Oliveira <bristot@redhat.com> | 2017-01-03 12:42:42 +0100 |
---|---|---|
committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2017-01-03 16:11:12 -0300 |
commit | 074859184d770824f4437dca716bdeb625ae8b1c (patch) | |
tree | 92058008461cf11062e6897a331fff18b67005fd /tools/lib/traceevent/plugin_sched_switch.c | |
parent | 60437ac02f398e0ee0927748d4798dd5534ac90d (diff) |
tools lib traceevent: Fix prev/next_prio for deadline tasks
Currently, the sched:sched_switch tracepoint reports deadline tasks with
priority -1. But when reading the trace via perf script I've got the
following output:
# ./d & # (d is a deadline task, see [1])
# perf record -e sched:sched_switch -a sleep 1
# perf script
...
swapper 0 [000] 2146.962441: sched:sched_switch: swapper/0:0 [120] R ==> d:2593 [4294967295]
d 2593 [000] 2146.972472: sched:sched_switch: d:2593 [4294967295] R ==> g:2590 [4294967295]
The task d reports the wrong priority [4294967295]. This happens because
the "int prio" is stored in an unsigned long long val. Although it is
set as a %lld, as int is shorter than unsigned long long,
trace_seq_printf prints it as a positive number.
The fix is just to cast the val as an int, and print it as a %d,
as in the sched:sched_switch tracepoint's "format".
The output with the fix is:
# ./d &
# perf record -e sched:sched_switch -a sleep 1
# perf script
...
swapper 0 [000] 4306.374037: sched:sched_switch: swapper/0:0 [120] R ==> d:10941 [-1]
d 10941 [000] 4306.383823: sched:sched_switch: d:10941 [-1] R ==> swapper/0:0 [120]
[1] d.c
---
#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <linux/types.h>
#include <linux/sched.h>
struct sched_attr {
__u32 size, sched_policy;
__u64 sched_flags;
__s32 sched_nice;
__u32 sched_priority;
__u64 sched_runtime, sched_deadline, sched_period;
};
int sched_setattr(pid_t pid, const struct sched_attr *attr, unsigned int flags)
{
return syscall(__NR_sched_setattr, pid, attr, flags);
}
int main(void)
{
struct sched_attr attr = {
.size = sizeof(attr),
.sched_policy = SCHED_DEADLINE, /* This creates a 10ms/30ms reservation */
.sched_runtime = 10 * 1000 * 1000,
.sched_period = attr.sched_deadline = 30 * 1000 * 1000,
};
if (sched_setattr(0, &attr, 0) < 0) {
perror("sched_setattr");
return -1;
}
for(;;);
}
---
Committer notes:
Got the program from the provided URL, http://bristot.me/lkml/d.c,
trimmed it and included in the cset log above, so that we have
everything needed to test it in one place.
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/866ef75bcebf670ae91c6a96daa63597ba981f0d.1483443552.git.bristot@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/lib/traceevent/plugin_sched_switch.c')
-rw-r--r-- | tools/lib/traceevent/plugin_sched_switch.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/tools/lib/traceevent/plugin_sched_switch.c b/tools/lib/traceevent/plugin_sched_switch.c index f1ce60065258..ec30c2fcbac0 100644 --- a/tools/lib/traceevent/plugin_sched_switch.c +++ b/tools/lib/traceevent/plugin_sched_switch.c @@ -111,7 +111,7 @@ static int sched_switch_handler(struct trace_seq *s, trace_seq_printf(s, "%lld ", val); if (pevent_get_field_val(s, event, "prev_prio", record, &val, 0) == 0) - trace_seq_printf(s, "[%lld] ", val); + trace_seq_printf(s, "[%d] ", (int) val); if (pevent_get_field_val(s, event, "prev_state", record, &val, 0) == 0) write_state(s, val); @@ -129,7 +129,7 @@ static int sched_switch_handler(struct trace_seq *s, trace_seq_printf(s, "%lld", val); if (pevent_get_field_val(s, event, "next_prio", record, &val, 0) == 0) - trace_seq_printf(s, " [%lld]", val); + trace_seq_printf(s, " [%d]", (int) val); return 0; } |