ffc team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Tue, Feb 24, 2009 at 05:04:50PM +0100, Anders Logg wrote:
> On Tue, Feb 24, 2009 at 03:37:31PM +0100, Kristian Oelgaard wrote:
> > Quoting FFC <ffc@xxxxxxxxxx>:
> > 
> > > One or more new changesets pushed to the primary ffc repository.
> > > A short summary of the last three changesets is included below.
> > > 
> > > changeset:   1328:83a16cff359ac9faf01d3af927e8d88a6005663e
> > > tag:         tip
> > > user:        "Kristian Oelgaard <k.b.oelgaard@xxxxxxxxxx>"
> > > date:        Tue Feb 24 15:33:18 2009 +0100
> > > files:       ffc/common/constants.py ffc/jit/jit.py ffc/jit/jitobject.py
> > > test/verify_tensors/test.py
> > > description:
> > > Added option 'compiler' to FFC_OPTIONS, default is ffc. The JIT compiler uses
> > > this to determine if the standard FFC compiler or the UFL compiler should be
> > > used.
> > 
> > I ran all tests in DOLFIN and nothing seems to be broken. I fixed this by
> > calling jit_object.signature() (to generate jit_object.form_data) BEFORE
> > checking cache. If this is somehow unsafe, we need to come up with a different
> > approach. I just think that it will introduce a small overhead?
> > 
> > Kristian
> 
> This was the problem I ran into when trying to fix the bug in jit.py
> before release. I couldn't figure out how to solve it without doing as
> you say, namely to generate the signature before checking the cache.
> 
> But this should be avoided. Computing the signature may actually take
> some time. There are two levels of cache (although I don't know the
> details of this now that it has moved into Instant): one in-memory
> cache and one disk cache. The in-memory cache does not require the
> signature, it just looks at the id() of the form which is faster
> than computing and comparing signatures.
> 
> Why is this change needed for compilation of UFL forms?

I've added a unit test for checking the speed of the JIT compiler and
it breaks now after the change to jit.py.

Before change:

  JIT in-memory cache: 0.000190019607544
  JIT disk cache:      0.028265953064

After change:

  JIT in-memory cache: 0.0181729793549
  JIT disk cache:      0.0284857749939

-- 
Anders

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