Xenofon Antidides wrote:
----- Original Message ----
From: Ingo Molnar <[EMAIL PROTECTED]>
To: Con Kolivas <[EMAIL PROTECTED]>
Cc: linux list <linux-kernel@vger.kernel.org>; Andrew Morton <[EMAIL PROTECTED]>;
Mike Galbraith <[EMAIL PROTECTED]>
Sent: Thursday, March 29, 2007 9:22:49 PM
Subject: [test] hackbench.c interactivity results: vanilla versus SD/RSDL
* Ingo Molnar <[EMAIL PROTECTED]> wrote:
* Con Kolivas <[EMAIL PROTECTED]> wrote:
I'm cautiously optimistic that we're at the thin edge of the bugfix
wedge now.
[...]
and the numbers he posted:
http://marc.info/?l=linux-kernel&m=117448900626028&w=2
We been staring at these numbers for while now and we come to the conclusion
they wrong.
The test is f is 3 tasks, two on different and one on same cpu as sh here:
virgin 2.6.21-rc3-rsdl-smp
top - 13:52:50 up 7 min, 12 users, load average: 3.45, 2.89, 1.51
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ P COMMAND
6560 root 31 0 2892 1236 1032 R 82 0.1 1:50.24 1 sh
6558 root 28 0 1428 276 228 S 42 0.0 1:00.09 1 f
6557 root 30 0 1424 280 228 R 35 0.0 1:00.25 0 f
6559 root 39 0 1424 276 228 R 33 0.0 0:58.36 0 f
6560 sh is asking for 100% cpu on cpu number 1
6558 f is asking for 50% cpu on cpu number 1
6557 f is asking for 50% cpu on cpu number 0
6559 f is asking for 50% cpu on cpu number 0
So if 6560 and 6558 are asking for cpu from cpu number 1:
6560 wants 100% and 6558 wants 50%.
6560 should get 2/3 cpu 6558 should get 1/3 cpu
I don't think you can say that. If the 50% task alternated between
long periods of running and sleeping, then the end result should
approach a task that is sleeping for 50% of the time, and on the
CPU 25% of the time. As the periods get shorter, then the schedulers
will favour the 50% task relatively more, but details will depend on
implementation.
You could have an implementation that always gives runs the 50% task
when it becomes runnable, because it is decided that its priority is
higher because it has been sleeping.
The only thing you can really say is that the 50% task should get
between 25% and 50% (inclusive) CPU time.
--
SUSE Labs, Novell Inc.
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