[petsc-dev] CheckPointer

[Jed Brown]

Dave May <dave.mayhem23 at gmail.com> writes:

> Hey Jed,
>
> The overhead is big.
> Here are some numbers I generated which prompted Matt's email.
>
> All the total run times reported are almost entirely associated with matrix
> assembly.
> All builds used --with-debugging=yes
>
> Time (sec):           6.285e+00 [petsc v3.2]
> Time (sec):           1.966e+02 [petsc v3.4]
> Time (sec):           8.960e+00 [petsc v3.4 with a hacked checkptr.c which
> skips the checking]
>
> Calls to MatSetValue  5955066
> Calls to MatSetValues 11910132

Would removing the check only in MatSetValues be good enough?  Probably
a better alternative to my earlier suggestion would be

PetscCheckPointerPushFastRegion()
all the normal checks, possibly nested
PetscCheckPointerPopFastRegion()

Those would be inline functions that just increment and decrement a
global counter and PetscCheckPointer would only do the expensive check
when the counter was equal to 0.  And we can still have the run-time
parameter that checks "always" or "never".
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