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tracing: add global-clock option to provide cross CPU clock to traces

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Impact: feature to allow better serialized clock

This patch adds an option called "global-clock" that will allow
the tracer to switch to a slower but more accurate (across CPUs)
clock.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This commit is contained in:
Steven Rostedt 2009-03-17 18:09:55 -04:00
parent 37886f6a9f
commit af4617bdba
2 changed files with 31 additions and 4 deletions
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34
kernel/trace/trace.c
View file

@ -315,6 +315,7 @@ static const char *trace_options[] = {
"printk-msg-only",
"context-info",
"latency-format",
"global-clock",
NULL
};
@ -2251,6 +2252,34 @@ static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
return 0;
}
static void set_tracer_flags(unsigned int mask, int enabled)
{
/* do nothing if flag is already set */
if (!!(trace_flags & mask) == !!enabled)
return;
if (enabled)
trace_flags |= mask;
else
trace_flags &= ~mask;
if (mask == TRACE_ITER_GLOBAL_CLK) {
u64 (*func)(void);
if (enabled)
func = trace_clock_global;
else
func = trace_clock_local;
mutex_lock(&trace_types_lock);
ring_buffer_set_clock(global_trace.buffer, func);
if (max_tr.buffer)
ring_buffer_set_clock(max_tr.buffer, func);
mutex_unlock(&trace_types_lock);
}
}
static ssize_t
tracing_trace_options_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
@ -2278,10 +2307,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
int len = strlen(trace_options[i]);
if (strncmp(cmp, trace_options[i], len) == 0) {
if (neg)
trace_flags &= ~(1 << i);
else
trace_flags |= (1 << i);
set_tracer_flags(1 << i, !neg);
break;
}
}

1
kernel/trace/trace.h
View file

@ -667,6 +667,7 @@ enum trace_iterator_flags {
TRACE_ITER_PRINTK_MSGONLY = 0x10000,
TRACE_ITER_CONTEXT_INFO = 0x20000, /* Print pid/cpu/time */
TRACE_ITER_LATENCY_FMT = 0x40000,
TRACE_ITER_GLOBAL_CLK = 0x80000,
};
/*