"Gleb O. Raiko" wrote: > Carsten Langgaard wrote: > > > > "Gleb O. Raiko" wrote: > > > Basically, requirement of uncached run makes hadrware logic much simpler > > > and allows to save silicon a bit. > > > > That could be true, but then again I suggest making specific cache routines for those > > CPUs. > > It would be a real performance hit for the rest of us, if we have to operate from > > uncached space. > > > > In theory, yes, there is a performance penalty. In practice, I doubt > this penalty is significant. Sure, Linux likes to flush cahces, not to > say more. But, did somebody measure the penalty of uncached runs? Even > with microbencnmarks like lmbench. Yes, I have tried running linux this way, because I wanted to eliminate the reason I sow cache problems on one of our tests chip, was due to execute the cache operating instruction from cached space. I didn't thought it was that big a penalty, because you are flushing the cache anyway, but I didn't had to run any benchmarks, so obviously was it when I booted my system. > > Regards, > Gleb. -- _ _ ____ ___ Carsten Langgaard Mailto:carstenl@mips.com |\ /|||___)(___ MIPS Denmark Direct: +45 4486 5527 | \/ ||| ____) Lautrupvang 4B Switch: +45 4486 5555 TECHNOLOGIES 2750 Ballerup Fax...: +45 4486 5556 Denmark http://www.mips.com
