Michael Buesch <[email protected]> wrote on 31/10/2009 17:42:54: > > On Saturday 31 October 2009 14:26:48 Joakim Tjernlund wrote: > > > > > > > On Friday 30 October 2009 16:08:55 Alessandro Rubini wrote: > > > > > > asm("eieio; sync"); > > > > > > > > > > Hmm... > > > > > : : : "memory" > > > > > > > > > > And, doesn't ";" start a comment in assembly? (no, not on powerpc > > > > it seems) > > > > > > > > Yes, I think the barrier is wrong. > > > > Please try with > > > > > > > > #define mb() __asm__ __volatile__("eieio\n sync\n" : : : > > > > "memory") > > > > > > That definition worked great. I must have missed the : : : "memory" bit > > > when > > > I was digging through code. > > > > > > Thanks, that gives me about a 2x speedup over the msync() calls. > > > > Exactly when should you use the barrier? At every access, > > every read or when changing from write to read? > > Well, it depends on the device you are accessing. I'll give you a small > pseudo example. > > mmio[0] = address; > mmio[1] = data; > mb(); > mmio[3] |= 0x01; /* This triggers an operation -> address=data */ > /* probably also need an mb() here, if the following code > * depends on the operation to be triggered. */
So anything that depends on the previous accesses needs a mb() hmm, the mmio[0] and mmio[1] are written in order I hope? Jocke _______________________________________________ Linuxppc-dev mailing list [email protected] https://lists.ozlabs.org/listinfo/linuxppc-dev
