> 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] > <mailto:[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. > > This email and any attachments are intended solely for the use of the named > recipients. If you are not the intended recipient you must not use, disclose, > copy or distribute this email or any of its attachments and should notify the > sender immediately and delete this email from your system. UK Research and > Innovation (UKRI) has taken every reasonable precaution to minimise risk of > this email or any attachments containing viruses or malware but the recipient > should carry out its own virus and malware checks before opening the > attachments. UKRI does not accept any liability for any losses or damages > which the recipient may sustain due to presence of any viruses. > <ksp_ex45_N511_cpu_6.txt>
