Re: [ANNOUNCE] Staircase Deadline cpu scheduler version 0.45

From: Willy Tarreau
Date: Sun Apr 22 2007 - 03:02:03 EST


On Sun, Apr 22, 2007 at 02:41:48PM +1000, Con Kolivas wrote:
> A significant bugfix for SMP balancing was just posted for the staircase
> deadline cpu scheduler which improves behaviour dramatically on any SMP
> machine.
>
> Thanks to Willy Tarreau for noticing likely fault point.
>
> Also requested was a version in the Makefile so this version of the patch
> adds -sd045 to the kernel version.

Con, I'm sorry, but it is worse with this one :-(

The lag when typing in xterms is even more noticeable and vmstat output
oscillates between 8 and 65, with idle rates around 50%, as you can see
below :

procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
9 0 0 0 922436 6392 57496 0 0 0 0 2 172 26 33 41
65 0 1 0 922436 6392 57496 0 0 0 0 0 132 23 37 40
66 0 0 0 922436 6392 57496 0 0 0 0 1 159 18 31 51
9 0 0 0 922436 6392 57496 0 0 0 0 0 166 24 37 40
68 0 0 0 922436 6392 57496 0 0 0 0 5 121 23 32 44
62 0 0 0 922576 6392 57496 0 0 0 0 0 161 17 29 53
8 0 0 0 922576 6392 57496 0 0 0 0 1 158 23 42 34
65 0 0 0 922576 6392 57496 0 0 0 0 1 92 17 33 50
52 0 2 0 922576 6392 57496 0 0 0 0 0 156 19 28 53
13 0 0 0 922576 6392 57496 0 0 0 0 8 171 25 44 30
65 0 0 0 922576 6392 57496 0 0 0 0 17 172 20 26 54
8 0 0 0 922576 6392 57496 0 0 0 0 4 188 22 31 47
22 0 0 0 922576 6392 57496 0 0 0 0 10 182 26 38 36
65 0 1 0 922576 6392 57496 0 0 0 0 8 107 18 28 54
8 0 0 0 922588 6424 57508 0 0 12 36 11 201 26 35 39
66 0 0 0 922588 6424 57508 0 0 0 0 11 115 22 36 43
61 0 0 0 922564 6424 57508 0 0 0 0 32 409 16 28 56
8 0 0 0 922564 6424 57508 0 0 0 0 19 224 24 42 34
65 0 0 0 922564 6436 57496 0 0 0 12 34 439 19 29 52
8 0 0 0 922564 6436 57496 0 0 0 0 28 320 18 26 56
20 0 0 0 922564 6436 57508 0 0 0 0 6 195 26 42 32

Renicing X or not does not change anything here.

I suspect that the bug you fixed was hiding another one :-/
If you want me to test another patch, feel free to ask.

Willy

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