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| author |   Brian Brooks <brian.brooks@arm.com> | 2018-01-09 16:39:07 -0600 |
|---|---|---|
| committer |   Damjan Marion <dmarion.lists@gmail.com> | 2018-01-30 13:23:31 +0000 |
| commit | c0379aec241c78fe07074fa7e63a5009a4e7944a (patch) | |
| tree | 2a217cbdc9b65a89b9b6c68d20b6548d36649c3e /src/vppinfra/time.c | |
| parent | bc39e3470c04af56bc45756585b848cd448b990b (diff) | |
Arm system counter cleanup
Add some description and cleanup code that uses Arm system counter.
Change-Id: Ie1fe00e3e4b5d98867617b7b0184ac526e333c53
Signed-off-by: Brian Brooks <brian.brooks@arm.com>
Diffstat (limited to 'src/vppinfra/time.c')
| -rw-r--r-- | src/vppinfra/time.c | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/src/vppinfra/time.c b/src/vppinfra/time.c index 770ed8b6807..1626ff4ed38 100644 --- a/src/vppinfra/time.c +++ b/src/vppinfra/time.c @@ -142,17 +142,20 @@ done: f64 os_cpu_clock_frequency (void) { +#if defined (__aarch64__) + /* The system counter increments at a fixed frequency. It is distributed + * to each core which has registers for reading the current counter value + * as well as the clock frequency. The system counter is not clocked at + * the same frequency as the core. */ + u32 hz; + asm volatile ("mrs %0, cntfrq_el0":"=r" (hz)); + return (f64) hz; +#endif f64 cpu_freq; if (clib_cpu_supports_invariant_tsc ()) return estimate_clock_frequency (1e-3); -#if defined (__aarch64__) - u64 tsc; - asm volatile ("mrs %0, CNTFRQ_EL0":"=r" (tsc)); - return (f64) tsc; -#endif - /* First try /sys version. */ cpu_freq = clock_frequency_from_sys_filesystem (); if (cpu_freq != 0) |