On Mon, 15 Oct 2007, H. Peter Anvin wrote: > Mikulas Patocka wrote: > > > > I know about unordered stores (movnti & similar) --- they basically use > > write-combining method on memory that is normally write-back --- and they > > need sfence. But which one instruction does unordered load and needs > > lefence? > > > > PREFETCHNTA.
PREFETCH* doesn't change program semantics. The processor is allowed to ignore prefetch instruction if it doesn't have resources needed for prefetch. It not ordered wrt. fences. PREFETCHNTA was implemented as prefetch into L1 cache and omitting L2 cache on Pentium 3 and M --- and it is implemented as prefetch into L2 cache on other --- do it doesn't really use any special buffers. Mikulas > -hpa > - 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/
