On 2024-09-12 17:11, Jerin Jacob wrote:
On Thu, Sep 12, 2024 at 6:50 PM Mattias Rönnblom <hof...@lysator.liu.se> wrote:
On 2024-09-12 15:09, Jerin Jacob wrote:
On Thu, Sep 12, 2024 at 2:34 PM Mattias Rönnblom
<mattias.ronnb...@ericsson.com> wrote:
Add basic micro benchmark for lcore variables, in an attempt to assure
that the overhead isn't significantly greater than alternative
approaches, in scenarios where the benefits aren't expected to show up
(i.e., when plenty of cache is available compared to the working set
size of the per-lcore data).
Signed-off-by: Mattias Rönnblom <mattias.ronnb...@ericsson.com>
---
app/test/meson.build | 1 +
app/test/test_lcore_var_perf.c | 160 +++++++++++++++++++++++++++++++++
2 files changed, 161 insertions(+)
create mode 100644 app/test/test_lcore_var_perf.c
+static double
+benchmark_access_method(void (*init_fun)(void), void (*update_fun)(void))
+{
+ uint64_t i;
+ uint64_t start;
+ uint64_t end;
+ double latency;
+
+ init_fun();
+
+ start = rte_get_timer_cycles();
+
+ for (i = 0; i < ITERATIONS; i++)
+ update_fun();
+
+ end = rte_get_timer_cycles();
Use precise variant. rte_rdtsc_precise() or so to be accurate
With 1e7 iterations, do you need rte_rdtsc_precise()? I suspect not.
I was thinking in another way, with 1e7 iteration, the additional
barrier on precise will be amortized, and we get more _deterministic_
behavior e.s.p in case if we print cycles and if we need to catch
regressions.
If you time a section of code which spends ~40000000 cycles, it doesn't
matter if you add or remove a few cycles at the beginning and the end.
The rte_rdtsc_precise() is both better (more precise in the sense of
more serialization), and worse (because it's more costly, and thus more
intrusive).
You can use rte_rdtsc_precise(), rte_rdtsc(), or gettimeofday(). It
doesn't matter.
Furthermore, you may consider replacing rte_random() in fast path to
running number or so if it is not deterministic in cycle computation.
rte_rand() is not used in the fast path. I don't understand what you
mean by "running number".
