On 03.09.15 15:29, Savolainen, Petri (Nokia - FI/Espoo) wrote:
There are many example apps that actually want to measure execution time in CPU cycles, not in nsec. Time API and CPU (cycle) API updates are linked together. Real CPU cycle cases must not converted to use time API, but to use a new odp_cpu_cycle() count API first. Then what is left should be actual time API use cases.
Let me look at CPU API first. I hesitate to answer because of freq scaling. I have filling that there is not so very well. And yes, probably I should move part of this changes in preparation series.
-----Original Message----- From: lng-odp [mailto:lng-odp-boun...@lists.linaro.org] On Behalf Of ext Ivan Khoronzhuk Sent: Thursday, September 03, 2015 12:11 AM To: lng-odp@lists.linaro.org Subject: [lng-odp] [odp-lng] [Patch v3 1/3] api: time: unbind CPU cycles from time API Current time API supposes that frequency of counter is equal to CPU frequency. But that's not always true, for instance, in case if no access to CPU cycle counter, another hi-resolution timer can be used, and it`s rate can be different from CPU rate. There is no big difference in which cycles to measure time, the better hi-resolution timer the better measurements. So, unbind CPU cycle counter from time API by eliminating word "cycle" as it's believed to be used with CPU. Also add new opaque type for time odp_time_t, as it asks user to use API and abstracts time from units. New odp_time_t requires several additional API functions to be added: odp_time_t odp_time_sum(odp_time_t t1, odp_time_t t2); int odp_time_cmp(odp_time_t t1, odp_time_t t2); uint64_t odp_time_to_u64(odp_time_t hdl); Also added new definition that represents 0 ticks for time - ODP_TIME_NULL. It can be used instead of odp_time_from_ns(0) for comparison and initialization. This patch only changes used time API, it doesn't change used var names for simplicity. Signed-off-by: Ivan Khoronzhuk <ivan.khoronz...@linaro.org> ---/* diff --git a/test/performance/odp_scheduling.c b/test/performance/odp_scheduling.c index 2a7e531..5859460 100644 --- a/test/performance/odp_scheduling.c +++ b/test/performance/odp_scheduling.c @@ -183,9 +183,10 @@ static int test_alloc_single(int thr, odp_pool_t pool) { int i; odp_buffer_t temp_buf; - uint64_t t1, t2, cycles, ns; + odp_time_t t1, t2, cycles; + uint64_t ns; - t1 = odp_time_cycles(); + t1 = odp_time(); for (i = 0; i < ALLOC_ROUNDS; i++) { temp_buf = odp_buffer_alloc(pool); @@ -198,12 +199,12 @@ static int test_alloc_single(int thr, odp_pool_t pool) odp_buffer_free(temp_buf); } - t2 = odp_time_cycles(); - cycles = odp_time_diff_cycles(t1, t2); - ns = odp_time_cycles_to_ns(cycles); + t2 = odp_time(); + cycles = odp_time_diff(t1, t2); + ns = odp_time_to_ns(cycles); printf(" [%i] alloc_sng alloc+free %"PRIu64" cycles, %"PRIu64" ns\n", - thr, cycles/ALLOC_ROUNDS, ns/ALLOC_ROUNDS); + thr, odp_time_to_u64(cycles) / ALLOC_ROUNDS, ns / ALLOC_ROUNDS); return 0;For example, this is really measuring average CPU cycles (with or without freq scaling). The ns conversion can be removed. -Petri
-- Regards, Ivan Khoronzhuk _______________________________________________ lng-odp mailing list lng-odp@lists.linaro.org https://lists.linaro.org/mailman/listinfo/lng-odp
