<div dir="ltr">Hello, <div><br></div><div>the develop branch of the opengate git repository has been updated : Gate is now compatible with Geant4 10.0 <span style="font-family:arial,sans-serif;font-size:13px">(must be compiled with GEANT4_BUILD_</span><span style="font-family:arial,sans-serif;font-size:13px">MULTITHREADED=false). </span><br>
</div><div><span style="font-family:arial,sans-serif;font-size:13px"><br></span></div><div><span style="font-family:arial,sans-serif;font-size:13px">feedback welcome, </span></div><div><span style="font-family:arial,sans-serif;font-size:13px">have fun, </span></div>
<div><span style="font-family:arial,sans-serif;font-size:13px">David</span></div><div><span style="font-family:arial,sans-serif;font-size:13px"><br></span></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">
On Mon, Dec 2, 2013 at 2:37 PM, Marc Verderi <span dir="ltr"><<a href="mailto:verderi@in2p3.fr" target="_blank">verderi@in2p3.fr</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear Ian,<br>
<br>
Just a few words to let you know about some feature of the Geant4 10.0 MT, and to partly answer your question. Geant4 10.0, which includes this MT capability, will be released in a few days. The MT scheme adopted is to process events (in Geant4 sense) in parallel, each thread dealing with a set of events, and sharing geometry and physics tables among the threads, to minimize the memory footprint.<br>
<br>
GATE will certainly need an adaptation. This is of course critical, but requires only a few lines of code. The G4RunManager as to be replaced by the G4MTRunManager. Users' actions (primary generator action, stepping action, event action, and run action if needed) become thread local actions : one instance of each of these actions is instantiated per thread. Sensitive detectors and fields become also thread local, and have to be instantiated in a new method of the detector construction : ConstructSDandField() which is executed once for each thread. In this way, events can be processed independently, in parallel. The overall mechanics is controlled by a master thread, the one launched at the application startup, and which then spawn the slave threads at event loop start.<br>
<br>
What will be needed also is an examination of the "static" data members in the GATE classes : some of them would be static as known in the master and slave threads, some others will be static but with a thread local scope and will need some adaptation. Helper classes in the Geant4 MT version exist to help doing an easy transformation of, for example, a singleton to a thread-local singleton.<br>
All these transformations are compatible with a sequential processing (the up-to-now processing), and a MT-compliant code can be compiled as is for a sequential processing (provided the G4RunManager has been chosen).<br>
<br>
For information, tests performed on a 61 cores Intel Xeon Phi board allowed to go up to 244 threads (maximum possible number on this platform) for a single realistic application !<br>
<br>
Hoping I just whet your appetite ! ;)<br>
<br>
Best regards,<br>
Marc<div class="HOEnZb"><div class="h5"><br>
<br>
<br>
<br>
On 11/26/2013 03:07 PM, Porter Ian (RBV) NHS Christie Tr wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hello All,<br>
My understanding is that the next version of Geant4 (v10.0) will<br>
support multi-threading and will be released to production soon. We are<br>
keen to move over to this to avoid using multiple instances of GATE (1<br>
per CPU core) on our cluster. Can anyone tell me whether GATE will<br>
require an upgrade in order to work with Geant4 MT? If so, is there a<br>
timescale for the release of the new version? The last newsletter<br>
mentions GATE v7.0 with GPU support, which was due out by now but has<br>
not yet appeared. Is this being rewritten with a view to supporting<br>
Geant4 10.0 MT?<br>
<br>
Many Thanks,<br>
-- Ian.<br>
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