--- Gleb Natapov <[email protected]> wrote:
> On Wed, Dec 27, 2006 at 04:13:00PM +0100, Arjan van de Ven wrote:
> > The original p4 HT to a large degree suffered from a too small
> cache
> > that now was shared. SMT in general isn't per se all that different
> in
> > performance than dual core, at least not on a fundamental level,
> it's
> > all a matter of how many resources each thread has on average. With
> dual
> > core sharing the cache for example, that already is part HT.
> Putting the
> > "boundary" at HT-but-not-dual-core is going to be highly artificial
> and
> > while it may work for the current hardware, in general it's not a
> good
> > way of separating things (just look at the PowerPC processors,
> those are
> > highly SMT as well), and I suspect that your distinction is just
> going
> > to break all the time over the next 10 years ;) Or even today on
> the
> > current "large cache" P4 processors with HT it already breaks.
> (just
> > those tend to be the expensive models so more rare)
> >
> If I run two threads that are doing only calculations and very little
> or no
> IO at all on the same socket will modern HT and dual core be the same
> (or close) performance wise?
>
Hi Gleb,
this is a real interesting question. Ganglia is coming [originally]
from the HPC side of computing. At least in the past HT as implemented
on XEONs did help a lot. Running two CPU+memory-bandwith intensive
processes on the same physical CPU would at best result in a 50/50
performance split. So, knowing how many "real" CPUs are in a system is
interesting to us.
Other workloads (like lots of java threads doing mixed IO and CPU
stuff) of course can benefit from HT.
Cheers
Martin
------------------------------------------------------
Martin Knoblauch
email: k n o b i AT knobisoft DOT de
www: http://www.knobisoft.de
-
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]
