* Alexey Dobriyan ([EMAIL PROTECTED]) wrote: > On Fri, Jul 13, 2007 at 09:24:43PM -0400, Mathieu Desnoyers wrote: > > Immediate values provide a way to use dynamic code patching to update > > variables > > sitting within the instruction stream. It saves caches lines normally used > > by > > static read mostly variables. > > > kernel/Kconfig.immediate | 11 +++++++++++ > > NAK, if this immediate stuff is so super-cool¹ it should be default on. > > ¹ it isn't >
Hi Alexey, On embedded systems, the tradeoff is not the same. The immediate values trade a little bit of system memory (to keep the pointers to the variable and instruction as well as the size of the variable, only used when the variable is updated) in order to remove cache line hot paths. Also, embedded systems with physically read-only memory clearly does not want to enable this. Mathieu -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
