Re: Scheduler fairness problem on 2.6 series (Attn: Nick Piggin and others)

[<spaminos-ker@yahoo.com>]

--- Peter Williams <pwil3058@bigpond.net.au> wrote:
> I've just run your tests on my desktop and with max_ia_bonus at its 
> default value I see the "delta = 3" with 20 threads BUT when I set 
> max_ia_bonus to zero they stop (in both "eb" and "pb" mode).  So I then 
> reran the tests with 60 threads and zero max_ia_bonus and no output was 
> generated by your testdelay script in either "eb" or "pb" modes.  I 
> didn't try "sc" mode as I have a ZAPHOD kernel loaded (not HYDRA) but 
> Con has reported that the problem is absent in his latest patches so 
> I'll update the "sc" mode in HYDRA to those patches.
> 

I just tried the same test on spa-zaphod-linux 4.1 over 2.6.8-rc4

I also have messages with 20 threads "delta = 3" that go away when I set
max_ia_bonus to 0 (and stay off with 60 threads too) in "pb" mode.
But, unlike your desktop, the "eb" mode doesn't seem to get better by setting
max_ia_bonus to 0 on my machine, maybe I need to tweak something else? (even
though, the idea of tweaking for a given workload doesn't sound very good to
me).

The "pb" mode is very responsive with the system under heavy load, I like it :)

I will run some tests over the week end with the actual server to see the
effect of this patch on a more complex system.

Nicolas

PS: the machine I am using is a pure server, only accessible through ssh, so I
can not really tell the behavior under X.