Add check for invariant TSC on x86 and use TSC is default clock if reliable
TSC is by far the fastest clock we can use. Check the CPUID bits for
whether it is both constant rate AND synced across cores. If it is,
we can use it as our default clock source.
Fio will default to this clock source on x86 if no other clock source
is specifically given with clocksource= in the job file.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fio.h b/fio.h
index 3de3f00..de4ca4d 100644
--- a/fio.h
+++ b/fio.h
@@ -598,6 +598,7 @@
extern int fio_gtod_offload;
extern int fio_gtod_cpu;
extern enum fio_cs fio_clock_source;
+extern int fio_clock_source_set;
extern int warnings_fatal;
extern int terse_version;
extern int is_backend;