Christoph Hellwig <[EMAIL PROTECTED]> writes: > > I've done this a gazillion times before, so maybe instead of beeing a lazy > bastard you could look up mailinglist archive. It's not like this is the > first discussion of perfmon. But to get start look at the systems calls, > many of them are beasts like: > > int pfm_read_pmds(int fd, pfarg_pmd_t *pmds, int n) > > This is basically a read(2) (or for other syscalls a write) on something
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) Later a syscall might be needed with event multiplexing, but that seems more like a far away non essential feature. > else than the file descriptor provided to the system call. The right thing I don't like read/write for this too much. I think it's better to have individual syscalls. After all that is CPU state and having syscalls for that does seem reasonable. -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/
