On Wed, Mar 19, 2008 at 10:42 AM, Stefan Ring <[EMAIL PROTECTED]> wrote: > > On Mar 19, 2008 05:24 PM, Adam Olsen <[EMAIL PROTECTED]> wrote: > > > On Wed, Mar 19, 2008 at 10:09 AM, Stefan Ring <[EMAIL PROTECTED]> wrote: > > > Adam Olsen <rhamph <at> gmail.com> writes: > > > > > > > Can you try with a call to sched_yield(), rather than nanosleep()? > > > > It > > > > should have the same benefit but without as much performance hit. > > > > > > > > If it works, but is still too much hit, try tuning the > > > > checkinterval > > > > to see if you can find an acceptable throughput/responsiveness > > > > balance. > > > > > > > > > > I tried that, and it had no effect whatsoever. I suppose it would > > > make an effect > > > on a single CPU or an otherwise heavily loaded SMP system but that's > > > not the > > > secnario we care about. > > > > So you've got a lightly loaded SMP system? Multiple threads all > > blocked on the GIL, multiple CPUs to run them, but only one CPU is > > active? I that case I can imagine how sched_yield() might finish > > before the other CPUs wake up a thread. > > > > A FIFO scheduler would be the right thing here, but it's only a short > > term solution. Care for a long term solution? ;) > > > > http://code.google.com/p/python-safethread/ > > I've already seen that but it would not help us in our current > situation. The performance penalty really is too heavy. Our system is > slow enough already ;). And it would be very difficult bordering on > impossible to parallelize Plus, I can imagine that all extension modules > (and our own code) would have to be adapted. > > The FIFO scheduler is perfect for us because the load is typically quite > low. It's mostly at those times when someone runs a lengthy calculation > that all other users suffer greatly increased response times.
So you want responsiveness when idle but throughput when busy? Are those calculations primarily python code, or does a C library do the grunt work? If it's a C library you shouldn't be affected by safethread's increased overhead. -- Adam Olsen, aka Rhamphoryncus _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
