On Mon, Apr 20, 2009 at 02:00:56PM +0100, Robert Watson wrote: > > On Mon, 20 Apr 2009, John Baldwin wrote: > > >> Now that the kernel defines CACHE_LINE_SIZE in machine/param.h, use > >> that definition in the custom locking code for the run-time linker > >> rather than local definitions. > > > >Perhaps CACHE_LINE_SIZE for ia64 and sparc64 should be 128 since that is > >what rtld used? > > I'm happy with whatever size the platform maintainers would like. I've > changed ia64, sparc64, and sun4v kernel CACHE_LINE_SIZE definitions to 128, > and powerpc was already 128, but left the others at 64 bytes until such > time as we have some useful numbers or informat ionto suggest another > choice would be better. All I'm really looking for here is a baseline > constant to use, I have no particular vested interest in specific values > for the constants. >
For sparc64 the cache line size should be ideally determined at runtime using Open Firmware, however I'm not aware of a sun4u CPU having a L1 data- or instruction cache line size greater than 32 bytes though. Some of them have a prefetch cache with a line size of 64 bytes though which besides for the prefetch instructions is used autonomously by the CPU when fetching from the L2 cache (which can have a line size of up to 512 bytes AFAICT). I'm not aware how relevant this is for the intended use of CACHE_LINE_SIZE, but a value of of 64 seems appropriate for sparc64 in order also cover the prefetch cache. Marius _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
