On Wed, 25 Sep 2019 14:08:23 +0300
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@xxxxxxxxx> wrote:
> "trace-cmd reset" command should put all ftrace config to its default
> state, but trace cpumask was not reseted. The patch sets cpumask to
> its default value - all CPUs are enabled for tracing.
>
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@xxxxxxxxx>
> ---
> tracecmd/trace-record.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
> index 69de82a..c41f55f 100644
> --- a/tracecmd/trace-record.c
> +++ b/tracecmd/trace-record.c
> @@ -4096,6 +4096,24 @@ static void reset_clock(void)
> write_instance_file(instance, "trace_clock", "local", "clock");
> }
>
> +static void reset_cpu_mask(void)
> +{
> + char str[24];
> + int cpumask = 0;
> + int cpus = count_cpus();
> + struct buffer_instance *instance;
> +
> + while (cpus--) {
> + cpumask <<= 1;
> + cpumask |= 1;
> + }
First, you can accomplish the same with:
(1 << cpus) - 1;
But then this only works if we have less than 32 CPUs.
What we would want is:
int fullwords;
char *buf;
int bits;
int cpus;
int len;
fullwords = cpus / 32;
bits = cpus % 32;
len = (fullwords + 1) * 8;
buf = malloc(len + 1);
buf[0] = '\0';
if (bits)
sprintf(buf, "%x", (1 << bits) - 1);
while (fullwords-- > 0)
strcat(buf, "ffffffff");
Because we may run this on machines with 1000s of CPUs!
(BTW, I tested the above under valgrind with the following values:
1 31 32 33 126 127 128 129 with no memory leaks and the results
looked good)
-- Steve
> + if (snprintf(str, 24, "%x", cpumask) <= 0)
> + return;
> +
> + for_all_instances(instance)
> + write_instance_file(instance, "tracing_cpumask", str, "cpumask");
> +}
> +
> static void reset_event_pid(void)
> {
> add_event_pid("");
> @@ -4808,6 +4826,7 @@ void trace_reset(int argc, char **argv)
> reset_clock();
> reset_event_pid();
> reset_max_latency_instance();
> + reset_cpu_mask();
> tracecmd_remove_instances();
> clear_func_filters();
> /* restore tracing_on to 1 */
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