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/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
