Hi Bruce and Richard, Yes, as Richard pointed out, I just wanted to know the numbers for input to Amdahl's law, if you have already something, to figure out the maximum expected speedup using multiple processors/cores.
As for improvements of em_reg, I'll try to split each transform as well as parallelize the energy evaluation. Thank you for your comments. Akio (2012/07/04 5:21), R Edgar wrote: > On Tue, Jul 3, 2012 at 3:48 PM, Bruce Fischl <fis...@nmr.mgh.harvard.edu> > wrote: > >> I think that the theoretical ratio is much bigger than what you would be >> able to achieve in practice. It's hard to compute exactly, but for example >> for em_reg it should be the number of samples (which are processed >> independently), so something on the order of 1000. For ca_reg it should be >> bigger, but it's a bit more complicated as things aren't independent. > I _hope_ that the OpenMP version of mri_em_reg doesn't just try > parallelising the energy evaluation - it would be better to split each > transform off as a separate work item for handling by the available > threads (similar to what I did on the extra-fast GPU version). This > keeps the individual pieces of work big, which is good for CPUs > > I think that what Akio's after are the numbers to plug into Amdahl's > Law. I don't think that these are easy to work out for anything in > Freesurfer. But you can put timers around the parallel sections, and > see what speed up you get on those. > > HTH, > > Richard > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer > > > The information in this e-mail is intended only for the person to whom it is > addressed. If you believe this e-mail was sent to you in error and the e-mail > contains patient information, please contact the Partners Compliance HelpLine > at > http://www.partners.org/complianceline . If the e-mail was sent to you in > error > but does not contain patient information, please contact the sender and > properly > dispose of the e-mail. > > > _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
