[ET Trac] [Einstein Toolkit] #1718: MemSpeed: Re-use allocated memory
Einstein Toolkit
trac-noreply at einsteintoolkit.org
Wed Jan 23 10:35:39 CST 2019
#1718: MemSpeed: Re-use allocated memory
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Reporter: Erik Schnetter | Owner: (none)
Type: enhancement | Status: new
Priority: minor | Milestone:
Component: EinsteinToolkit thorn | Version: development version
Resolution: | Keywords:
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Comment (by Roland Haas):
I have made a simple attempt at this and limited the amount of memory used
(per rank) to 1GB which should be much larger than the first level of
cache for a while still. The largest cache like memory (see
https://en.wikipedia.org/wiki/CPU_cache#MULTILEVEL) would be the eDRAM on
Haswell CPUs with integrated graphics which is apparently 128 MB.
Note that this renders the {{{skip_largemem_benchmarks}}} options somewhat
redundant, though not fully since {{{skip_largemem_benchmarks}}} would
trigger on nodes with less than 4GB of memory per MPI rank used. It does
become redundant on "typical" clusters though since we use only a small
number of MPI ranks per node.
The test still takes approximately 2min on my workstation, though at least
1min of that is not the main memory test. This long runtime is probably a
measure of how slow the CPUs in my workstation are is by now (certainly
compared to the amount of memory in it).
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Ticket URL: <https://trac.einsteintoolkit.org/ticket/1718#comment:4>
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