[v4] timer: don't check tsc flags in secondary processes
Checks
Commit Message
check_tsc_flags() parses /proc/cpuinfo and prints
warning messages if any cores don't have constant_tsc
and nonstop_tsc. It has no functional meaning.
This consumes a noticeable amount of time in
secondary processes - on my test system, it consumes
21ms out of the 66ms total execution time for
rte_eal_init().
So let's just skip checking these flags in secondary
processes. Since the primary process is already
parsing the entirety of /proc/cpuinfo, the warning
printed in the primary process should be sufficient.
Signed-off-by: Jim Harris <james.r.harris@intel.com>
---
lib/librte_eal/linux/eal/eal_timer.c | 9 +++++++++
1 file changed, 9 insertions(+)
Comments
On Mon, 19 Aug 2019 02:42:10 -0700
Jim Harris <james.r.harris@intel.com> wrote:
> check_tsc_flags() parses /proc/cpuinfo and prints
> warning messages if any cores don't have constant_tsc
> and nonstop_tsc. It has no functional meaning.
> This consumes a noticeable amount of time in
> secondary processes - on my test system, it consumes
> 21ms out of the 66ms total execution time for
> rte_eal_init().
>
> So let's just skip checking these flags in secondary
> processes. Since the primary process is already
> parsing the entirety of /proc/cpuinfo, the warning
> printed in the primary process should be sufficient.
>
> Signed-off-by: Jim Harris <james.r.harris@intel.com>
Since all it does is print a warning, I would argue the code is useless
anyway and should just be removed. The warning doesn't provide any
indication of what to do for users; or even tell them what the effect is.
@@ -198,6 +198,15 @@ check_tsc_flags(void)
char line[512];
FILE *stream;
+ if (rte_eal_process_type() != RTE_PROC_PRIMARY) {
+ /* This function just prints warnings if TSC is not constant
+ * and has no functional meaning. It also checks *all* cores
+ * on the system, not just the ones configured for this process.
+ * So don't bother rechecking again in secondary processes.
+ */
+ return;
+ }
+
stream = fopen("/proc/cpuinfo", "r");
if (!stream) {
RTE_LOG(WARNING, EAL, "WARNING: Unable to open /proc/cpuinfo\n");