Re: [PATCH] 2.6.0 batch scheduling, HT aware

[davidsen@tmr.com (bill davidsen)]

In article <200312272215.01563.kernel@kolivas.org>,
Con Kolivas  <kernel@kolivas.org> wrote:
| On Sat, 27 Dec 2003 22:09, Pavel Machek wrote:
| > So... even on normal SMP,
| > "task-on-other-cpu-slows-down-task-on-this-cpu" effect exists. Okay,
| > it is not as visible as on HT machine (50% slowdown), but its
| > definitely there.
| 
| Sure but I think we're getting pedantic here. The problem is really simple - a 
| uniprocessor HT desktop booted in SMP mode feels half the speed while running 
| setiathome (or video encoding or whatever cpu bound task) compared to booting 
| it in UP mode. So, ironically, enabling the HT makes the machine feel slower 
| when running multiple tasks. And there will be a heck of a lot of these in 
| the future.

Let me put forth a thought, without a solution. In the case you
describe, what is needed, and not provided in hardware, is a way to do
priority within the CPU, so in the case of a contested resource there is
a way to ensure the process we wish wins.

Since that seems unavailable in Intel, do other CPUs do better (or
different)?
-- 
bill davidsen <davidsen@tmr.com>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.