pthread_mutex_timedlock on sparc64
kris at obsecurity.org
Thu Apr 20 22:02:38 UTC 2006
On Thu, Apr 20, 2006 at 05:52:19PM -0400, Miles Nordin wrote:
> >>>>> "kk" == Kris Kennaway <kris at obsecurity.org> writes:
> kk> In practise libthr is the fastest thread package, although
> kk> there must still be some reason we don't make it the default.
> thanks for the answers. makes sense, I think I've finally got it.
> For those forced to read all my noise today that haven't already heard
> this 1:1 vs MxN thing debated to death, this is the last thing I read
> about it:
> ``This is not to say that a good implementation of MxN model is
> impossible, but simply that a good 1:1 implementation is probably
> sufficient. This paper does not attempt a discussion of the
> relative merits of the MxN and 1:1 threading models. The basic
> thesis is that the quality of an implementation is often more
> The context is, a bunch of papers were published since 1993 showing
> that MxN threads were the most performant, and FreeBSD kse, Solaris
> threads between 2.6 and 2.8, threads in OSF/1 (I think the kse guys
> cited some Digital paper?), and NetBSD Scheduler Activations are all
> based on the design in the original paper cited at the end of kse(2).
> Sun scrapped scheduler activations in Solaris 2.9. They had to write
> the above advertisement PDF to convince people who'd read all that
> research since '93 that the 1:1 threads really were performant, and
> that they didn't just wuss out after too many bugs and revert to a
> slow, obvious EnTee/Linux style thread subsystem.
As I said previously, the 1:1 implementation in FreeBSD is also
usually faster (often much faster) than M:N. AFAIK, this is partly
due to the unavoidability (at least on architectures like x86) of
doing a syscall on thread context switch to save TLS state (this was
not addressed in the SA papers), which is what a scheduler
activations-like design was supposed to avoid.
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