On Thu, Sep 30, 2021 at 8:50 AM Karthikeyan Chockalingam - STFC UKRI < [email protected]> wrote:
When comparing the MatSolve data for
GPU
MatSolve 341 1.0 1.3009e+02 1.6 2.96e+11 1.0 0.0e+00 0.0e+00 0.0e+00 36 34 0 0 0 36 34 0 0 0 4536 4538 1 5.34e+02 0 0.00e+00 100
MatCUSPARSSolAnl 2 1.0 3.2338e+01 1.5 0.00e+00 0.0 0.0e+00 0.0e+00 0.0e+00 9 0 0 0 0 9 0 0 0 0 0 0 0 0.00e+00 0 0.00e+00 0
and CPU
MatSolve 352 1.0 1.3553e+02 1.0 1.02e+11 1.0 0.0e+00 0.0e+00 0.0e+00 35 34 0 0 0 35 34 0 0 0 4489
the time spent is almost the same for this preconditioner. Look like MatCUSPARSSolAnl is called only *twice* (since I am running on two cores)
mpirun -n 2 ./ex45 -log_summary -da_grid_x 511 -da_grid_y 511 -da_grid_z 511 -dm_mat_type mpiaijcusparse -dm_vec_type mpicuda -ksp_type cg -pc_type bjacobi -ksp_monitor
So would it be fair to assume MatCUSPARSSolAnl is *not *accounted for in MatSolve and it is an exclusive event?
Looks like that. Thanks Matt
KSPSolve (53%) + PCSetup (16%) + DMCreateMat (23%) + MatCUSPARSSolAnl (9%) ~ 100 %
Best,
Karthik.
*From: *Matthew Knepley <[email protected]> *Date: *Wednesday, 29 September 2021 at 16:29 *To: *"Chockalingam, Karthikeyan (STFC,DL,HC)" < [email protected]> *Cc: *Barry Smith <[email protected]>, "[email protected]" < [email protected]> *Subject: *Re: [petsc-users] %T (percent time in this phase)
On Wed, Sep 29, 2021 at 10:18 AM Karthikeyan Chockalingam - STFC UKRI < [email protected]> wrote:
Thank you!
Just to summarize
KSPSolve (53%) + PCSetup (16%) + DMCreateMat (23%) + MatCUSPARSSolAnl (9%) ~ 100 %
You didn’t happen to mention how MatCUSPARSSolAnl is accounted for? Am I right in accounting for it as above?
I am not sure.I thought it might be the GPU part of MatSolve(). I will have to look in the code. I am not as familiar with the GPU part.
MatCUSPARSSolAnl 2 1.0 3.2338e+01 1.5 0.00e+00 0.0 0.0e+00 0.0e+00 0.0e+00 9 0 0 0 0 9 0 0 0 0 0 0 0 0.00e+00 0 0.00e+00 0
Finally, I believe the vector events, VecNorn, VecTDot, VecAXPY, and VecAYPX are mutually exclusive?
Yes.
Thanks,
Matt
Best,
Karthik.
*From: *Matthew Knepley <[email protected]> *Date: *Wednesday, 29 September 2021 at 11:58 *To: *"Chockalingam, Karthikeyan (STFC,DL,HC)" < [email protected]> *Cc: *Barry Smith <[email protected]>, "[email protected]" < [email protected]> *Subject: *Re: [petsc-users] %T (percent time in this phase)
On Wed, Sep 29, 2021 at 6:24 AM Karthikeyan Chockalingam - STFC UKRI < [email protected]> wrote:
Thank you Mathew. Now, it is all making sense to me.
From data file ksp_ex45_N511_gpu_2.txt
KSPSolve (53%) + KSPSetup (0%) = PCSetup (16%) + PCApply (37%).
However, you said “So an iteration would mostly consist of MatMult + PCApply, with some vector work”
1) You do one solve, but 2 KSPSetUp()s. You must be running on more than one process and using Block-Jacobi . Half the time is spent in the solve (53%)
KSPSetUp 2 1.0 5.3149e-01 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 2.4e+01 0 0 0 0 1 0 0 0 0 1 0 0 0 0.00e+00 0 0.00e+00 0
KSPSolve 1 1.0 1.5837e+02 1.1 8.63e+11 1.0 6.8e+02 2.1e+06 4.4e+03 53100100100 95 53100100100 96 10881 11730 1022 6.40e+03 1021 8.17e-03 100
2) The preconditioner look like BJacobi-ILU. The setup time is 16%, which is all setup of the individual blocks, and this is all used by the numerical ILU factorization.
PCSetUp 2 1.0 4.9623e+01 1.3 1.45e+09 1.0 0.0e+00 0.0e+00 0.0e+00 16 0 0 0 0 16 0 0 0 0 58 0 2 6.93e+03 0 0.00e+00 0 PCSetUpOnBlocks 1 1.0 4.9274e+01 1.3 1.45e+09 1.0 0.0e+00 0.0e+00 0.0e+00 15 0 0 0 0 15 0 0 0 0 59 0 2 6.93e+03 0 0.00e+00 0
MatLUFactorNum 1 1.0 4.6126e+01 1.3 1.45e+09 1.0 0.0e+00 0.0e+00 0.0e+00 14 0 0 0 0 14 0 0 0 0 63 0 2 6.93e+03 0 0.00e+00 0
MatILUFactorSym 1 1.0 2.5110e+00 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 0.0e+00 1 0 0 0 0 1 0 0 0 0 0 0 0 0.00e+00 0 0.00e+00 0
3) The preconditioner application takes 37% of the time, which is all solving the factors and recorded in MatSolve(). Matrix multiplication takes 4%.
PCApply 341 1.0 1.3068e+02 1.6 2.96e+11 1.0 0.0e+00 0.0e+00 0.0e+00 37 34 0 0 0 37 34 0 0 0 4516 4523 1 5.34e+02 0 0.00e+00 100
MatSolve 341 1.0 1.3009e+02 1.6 2.96e+11 1.0 0.0e+00 0.0e+00 0.0e+00 36 34 0 0 0 36 34 0 0 0 4536 4538 1 5.34e+02 0 0.00e+00 100
MatMult 341 1.0 1.0774e+01 1.1 2.96e+11 1.0 6.9e+02 2.1e+06 2.0e+00 4 34100100 0 4 34100100 0 54801 66441 2 5.86e+03 0 0.00e+00 100
4) The significant vector time is all in norms (11%) since they are really slow on the GPU.
VecNorm 342 1.0 6.2261e+01129.9 4.57e+10 1.0 0.0e+00 0.0e+00 6.8e+02 11 5 0 0 15 11 5 0 0 15 1466 196884 0 0.00e+00 342 2.74e-03 100
VecTDot 680 1.0 1.7107e+00 1.3 9.09e+10 1.0 0.0e+00 0.0e+00 1.4e+03 1 10 0 0 29 1 10 0 0 29 106079 133922 0 0.00e+00 680 5.44e-03 100
VecAXPY 681 1.0 3.2036e+00 1.7 9.10e+10 1.0 0.0e+00 0.0e+00 0.0e+00 1 11 0 0 0 1 11 0 0 0 56728 58367 682 5.34e+02 0 0.00e+00 100
VecAYPX 339 1.0 2.6502e+00 1.8 4.53e+10 1.0 0.0e+00 0.0e+00 0.0e+00 1 5 0 0 0 1 5 0 0 0 34136 34153 339 2.71e-03 0 0.00e+00 100
So the solve time is:
53% ~ 37% + 4% + 11%
and the setup time is about 16%. I was wrong about the SetUp time being included, as it is outside the event:
https://gitlab.com/petsc/petsc/-/blob/main/src/ksp/ksp/interface/itfunc.c#L8...
It looks like the remainder of the time (23%) is spent preallocating the matrix.
Thanks,
Matt
The MalMult event is 4 %. How does this event figure into the above equation; if preconditioning (MatMult + PCApply) is included in KSPSolve?
Best,
Karthik.
*From: *Matthew Knepley <[email protected]> *Date: *Wednesday, 29 September 2021 at 10:58 *To: *"Chockalingam, Karthikeyan (STFC,DL,HC)" < [email protected]> *Cc: *Barry Smith <[email protected]>, "[email protected]" < [email protected]> *Subject: *Re: [petsc-users] %T (percent time in this phase)
On Wed, Sep 29, 2021 at 5:52 AM Karthikeyan Chockalingam - STFC UKRI < [email protected]> wrote:
That was helpful. I would like to provide some additional details of my run on cpus and gpus. Please find the following attachments:
1. graph.pdf a plot showing overall time and various petsc events. 2. ksp_ex45_N511_cpu_6.txt data file of the log_summary 3. ksp_ex45_N511_gpu_2.txt data file of the log_summary
I used the following petsc options for cpu
mpirun -n 6 ./ex45 -log_summary -da_grid_x 511 -da_grid_y 511 -da_grid_z 511 -dm_mat_type mpiaij -dm_vec_type mpi -ksp_type cg -pc_type bjacobi -ksp_monitor
and for gpus
mpirun -n 1 ./ex45 -log_summary -da_grid_x 511 -da_grid_y 511 -da_grid_z 511 -dm_mat_type mpiaijcusparse -dm_vec_type mpicuda -ksp_type cg -pc_type bjacobi -ksp_monitor
to run the following problem
https://petsc.org/release/src/ksp/ksp/tutorials/ex45.c.html
From the above code, I see is there no individual function called KSPSetUp(), so I gather KSPSetDM, KSPSetComputeInitialGuess, KSPSetComputeRHS, kSPSetComputeOperators all are timed together as KSPSetUp. For this example, is KSPSetUp time and KSPSolve time mutually exclusive?
No, KSPSetUp() will be contained in KSPSolve() if it is called automatically.
In your response you said that
“PCSetUp() time may be in KSPSetUp() or it maybe in PCApply() it depends on how much of the preconditioner construction can take place early, so depends exactly on the preconditioner used.”
I don’t see a explicit call to PCSetUp() or PCApply() in ex45; so for this particular preconditioner (bjacobi) how can I tell how they are timed?
They are all inside KSPSolve(). If you have a preconditioned linear solve, the oreconditioning happens during the iteration. So an iteration would mostly
consist of MatMult + PCApply, with some vector work.
I am hoping to time KSP solving and preconditioning mutually exclusively.
I am not sure that concept makes sense here. See above.
Thanks,
Matt
Kind regards,
Karthik.
*From: *Barry Smith <[email protected]> *Date: *Tuesday, 28 September 2021 at 19:19 *To: *"Chockalingam, Karthikeyan (STFC,DL,HC)" < [email protected]> *Cc: *"[email protected]" <[email protected]> *Subject: *Re: [petsc-users] %T (percent time in this phase)
On Sep 28, 2021, at 12:11 PM, Karthikeyan Chockalingam - STFC UKRI < [email protected]> wrote:
Thanks for Barry for your response.
I was just benchmarking the problem with various preconditioner on cpu and gpu. I understand, it is not possible to get mutually exclusive timing.
However, can you tell if KSPSolve time includes both PCSetup and PCApply? And if KSPSolve and KSPSetup are mutually exclusive? Likewise for PCSetUp and PCApply.
If you do not call KSPSetUp() separately from KSPSolve() then its time is included with KSPSolve().
PCSetUp() time may be in KSPSetUp() or it maybe in PCApply() it depends on how much of the preconditioner construction can take place early, so depends exactly on the preconditioner used.
So yes the answer is not totally satisfying. The one thing I would recommend is to not call KSPSetUp() directly and then KSPSolve() will always include the total time of the solve plus all setup time. PCApply will contain all the time to apply the preconditioner but may also include some setup time.
Barry
Best,
Karthik.
*From: *Barry Smith <[email protected]> *Date: *Tuesday, 28 September 2021 at 16:56 *To: *"Chockalingam, Karthikeyan (STFC,DL,HC)" < [email protected]> *Cc: *"[email protected]" <[email protected]> *Subject: *Re: [petsc-users] %T (percent time in this phase)
On Sep 28, 2021, at 10:55 AM, Karthikeyan Chockalingam - STFC UKRI < [email protected]> wrote:
Hello,
I ran ex45 in the KPS tutorial, which is a 3D finite-difference Poisson problem. I noticed from the output from using the flag -log_summary that for various events their respective %T (percent time in this phase) do not add up to 100 but rather exceeds 100. So, I gather there is some overlap among these events. I am primarily looking at the events KSPSetUp, KSPSolve, PCSetUp and PCSolve. Is it possible to get a mutually exclusive %T or Time for these individual events? I have attached the log_summary output file from my run for your reference.
For nested solvers it is tricky to get the times to be mutually exclusive because some parts of the building of the preconditioner is for some preconditioners delayed until the solve has started.
It looks like you are using the default preconditioner options which for this example are taking more or less no time since so many iterations are needed. It is best to use -pc_type mg to use geometric multigrid on this problem.
Barry
Thanks!
Karthik.
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<ksp_ex45_N511_cpu_6.txt>
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--
What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
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--
What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
-- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>