On Tue, Feb 19, 2002 at 11:32:22PM -0500, Daniel Jacobowitz wrote: > > If you do use floating point, I think it is pretty common to have > > only process that uses fpu and runs for very long. In that case, > > leaving FPU owned by the process also saves quite a bit. > > Not true. For instance, on a processor with hardware FPU, setjmp() > will save FPU registers. That means most processes will actually end > up taking the FPU at least once. > It is true that almost all process will take FPU once, but that does not affect my statement unless you have a lot of programs come in and go away. On other hand, I do agree with Greg that hand-waving does not mean much here. It would be nice to have some performance data on a benchmark apps. Any good candidate? It should be easy to do a comparison. BTW, I just found out that almost all processes have their used_math bit set - this is because init uses math at the beginning and later all forked processes inherit that bit. Interesting - that also hides a couple of bugs related to if (!current->used) branch in do_cpu(). Jun
