On Wed, Nov 14, 2007 at 06:13:42AM -0800, Stephane Eranian wrote: > > At least for x86 and I suspect some 1other architectures we don't > > initially need a syscall at all for this. There is an instruction > > RDPMC who can read a performance counter just fine. It is also much > > faster and generally preferable for the case where a process measures > > events about itself. In fact it is essential for one of the use cases > > I would like to see perfmon used (replacement of RDTSC for cycle > > counting) > > > > This only works when counting (not sampling) and only for self-monitoring.
It works for global monitoring too. > > > Later a syscall might be needed with event multiplexing, but that seems > > more like a far away non essential feature. > > > On a machine with only two generic counters such as MIPS or Intel Core 2 Duo, > multiplexing offers some advantages. If NMI watchdog is enabled, then you drop > to one generic counter on on Core 2. NMI watchdog is off by default now. Yes longer term we might need multiplexing, but definitely not as first step. -Andi - 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/
