[Dune-devel] Speed influence of the UG heap

[Oliver Sander]

Dear users of UG & UGGrid,

you may have noticed that, since about a year ago, UG has an option that
disables the hand-coded memory handling and uses the operating system heap
instead.  Doing that has two advantages: there's no artificial upper limit
on grid sizes anymore, and valgrind will see more bugs.

However, the influence of this choice on the speed of UGGrid has been an open
question.  So last night I set out to do a measurement.  I wrote a code that
does nothing except local refinement and coarsening of a large 3d grid for a
few minutes.  (Ask me for the details if you are interested).  That is the
worst for memory management, because lots of small objects get allocated and
deallocated.  I tested on my Debian Jessie box with kernel 3.13.

Somewhat surprisingly (or maybe not), the operating system heap is actually
_faster_ than UG's internal heap.  My test program ran for 289 seconds with
the UG heap, but only for 252 seconds with the OS heap.  Which, I suppose
is not that surprising after all if you look at the design of the UG heap.

So I'll probably make the system heap the default in one of the next UG releases.

Cheers,
Oliver

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 534 bytes
Desc: OpenPGP digital signature
URL: <https://lists.dune-project.org/pipermail/dune-devel/attachments/20140326/8051743f/attachment.sig>