Hi Jiapeng,
Yes, using sys.GetTimerCollisionBroad() and sys.GetTimerCollisionNarrow() is
probably what you need. A few more explanations below, for completeness.
The BT_PROFILE is the Bullet internal profiling mechanism. You could use that
as well, but then you’ll have to consult their documentation or else look in
the code to understand which phases are timed and profiled exactly.
CH_PROFILE is a similar mechanism for a Chrono simulation (in fact, you will
see that the CH_PROFILE mimics the one in Bullet). CH_PROFILE produces a
profile hierarchy which includes measurements for the overall collision
detection, as well as the separate “children” timing measurements of the broad
and narrow phases (although the latter are currently only included for the
Bullet collision system and not yet for the Multicore collision detection
system – I’ll look into making this consistent at some point in the future).
In addition, we keep various timer objects (of type ChTimer) which are used to
measure the time spent in various phases of the Chrono solution. There are
timers managed by and available from ChSystem for the main solution stages
(overall step, advance, linear solver setup, linear solver solution, etc).
Those include a timer for the collision detection phase (over the last step);
in addition, you can access collision system implementation-specific timers to
get the breakdown for the broadphase and narrowphase timings (the two functions
you already mentioned).
The timing information provided by CH_PROFILE and by the various ChTimer
objects will be consistent (and, for the collision detection timers, so should
be CH_PROFILE and BT_PROFILE). You can see this for the Bullet code:
{
BT_PROFILE("computeOverlappingPairs"); <-- broadphase timing for
BT_PROFILE (measures time in current block)
CH_PROFILE("Broad-phase"); <-- broadphase timing for
CH_PROFILE (measures time in current block)
timer_collision_broad.start(); --
computeOverlappingPairs(); |--> broadphase ChTimer
(measures time between start and stop)
timer_collision_broad.stop(); --
}
cbtDispatcher* dispatcher = getDispatcher();
{
BT_PROFILE("dispatchAllCollisionPairs"); <-- narrowphase timing for
BT_PROFILE
CH_PROFILE("Narrow-phase"); <-- narrowphase timing for
CH_PROFILE
timer_collision_narrow.start(); --
if (dispatcher) |--> narrowphase ChTimer
dispatcher->dispatchAllCollisionPairs(...); |
timer_collision_narrow.stop(); --
}
Hope that this helps,
--Radu
From: [email protected] <[email protected]> On Behalf
Of Jiapeng Liu
Sent: Wednesday, December 6, 2023 7:44 PM
To: ProjectChrono <[email protected]>
Subject: [chrono] How can I get the timing info of Chrono
Hi Radu,
I am running the demo_MBS_collision_trimesh.cpp demo.
I wanna get the timing info spent in broad and narrow collision process
especially when I run the code in multiple threads.
Currently, I am using sys.GetTimerCollisionBroad() and
sys.GetTimerCollisionNarrow() to get the corresponding timing info. Is it the
correct way?
Plus, I find Chrono has different ways to profile the code.
1. ChTimer timer_step/ timer_advance/ timer_ls_solve;
2. CH_PROFILE("ComputeCollisions");
3. BT_PROFILE("performDiscreteCollisionDetection");
Could you please elaborate what are the differences among these three methods?
Which one should I use for multi-thread timing?
Thank you for your help in advance!
Best
Jiapeng
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