--- Jens Axboe <axboe@suse.de> wrote: > On Tue, Feb
11 2003, Jens Axboe wrote:
> > On Tue, Feb 11 2003, Jens Axboe wrote:
> > > > Write based loads hurt. No breakages, but
> needs tuning.
> > >
> > > That's not even as bad as I had feared. I'll try
> to do some tuning with
> > > contest locally.
> >
> > Here are my results, for 2.5.60 vanilla, 2.5.60 +
> cfq with default
> > quantum of 16 (what you tested, too), and 2.5.60 +
> cfq without quantum
> > setting. The latter should be the fairest, only
> moves one request from
> > the pending queues.
>
> Did runs with quantum values of 2,4,8 as well to see
> how it looks. Often
> the dbench runs got screwed, perhaps the signalling
> changes from 2.5.60
> is interfering?
>
> dbench_load.c:72: SYSTEM ERROR: No such process :
> could not kill pid 4842
>
> Anyways, here are the results:
>
> no_load:
> Kernel [runs] Time CPU% Loads
> LCPU% Ratio
> 2.5.60 2 31 177.4 0 0.0
> 1.00
> 2.5.60-cfq0 2 31 174.2 0 0.0
> 1.00
> 2.5.60-cfq16 2 31 177.4 0 0.0
> 1.00
> 2.5.60-cfq4 1 32 171.9 0 0.0
> 1.00
> 2.5.60-cfq8 2 31 174.2 0 0.0
> 1.00
> cacherun:
> Kernel [runs] Time CPU% Loads
> LCPU% Ratio
> 2.5.60 2 29 182.8 0 0.0
> 0.94
> 2.5.60-cfq0 2 28 192.9 0 0.0
> 0.90
> 2.5.60-cfq16 2 29 182.8 0 0.0
> 0.94
> 2.5.60-cfq4 1 29 186.2 0 0.0
> 0.91
> 2.5.60-cfq8 2 29 182.8 0 0.0
> 0.94
> process_load:
> Kernel [runs] Time CPU% Loads
> LCPU% Ratio
> 2.5.60 2 38 142.1 12 47.4
> 1.23
> 2.5.60-cfq0 2 41 129.3 16 61.0
> 1.32
> 2.5.60-cfq16 2 37 145.9 12 43.2
> 1.19
> 2.5.60-cfq4 1 36 150.0 11 44.4
> 1.12
> 2.5.60-cfq8 2 38 142.1 13 47.4
> 1.23
> ctar_load:
> Kernel [runs] Time CPU% Loads
> LCPU% Ratio
> 2.5.60 2 38 147.4 0 0.0
> 1.23
> 2.5.60-cfq0 2 36 155.6 0 0.0
> 1.16
> 2.5.60-cfq16 2 36 155.6 0 0.0
> 1.16
> 2.5.60-cfq4 1 36 155.6 0 0.0
> 1.12
> 2.5.60-cfq8 2 37 151.4 0 0.0
> 1.19
> xtar_load:
> Kernel [runs] Time CPU% Loads
> LCPU% Ratio
> 2.5.60 2 40 140.0 0 2.5
> 1.29
> 2.5.60-cfq0 2 37 148.6 0 2.7
> 1.19
> 2.5.60-cfq16 2 40 137.5 0 2.5
> 1.29
> 2.5.60-cfq4 1 37 148.6 0 2.7
> 1.16
> 2.5.60-cfq8 2 38 147.4 0 2.6
> 1.23
> io_load:
> Kernel [runs] Time CPU% Loads
> LCPU% Ratio
> 2.5.60 2 93 61.3 2 14.0
> 3.00
> 2.5.60-cfq0 4 103 54.4 2 12.6
> 3.32
> 2.5.60-cfq16 2 264 21.6 12 19.9
> 8.52
> 2.5.60-cfq4 1 97 57.7 3 15.5
> 3.03
> 2.5.60-cfq8 2 135 42.2 5 16.3
> 4.35
> read_load:
> Kernel [runs] Time CPU% Loads
> LCPU% Ratio
> 2.5.60 2 40 140.0 0 5.0
> 1.29
> 2.5.60-cfq0 2 39 143.6 0 5.1
> 1.26
> 2.5.60-cfq16 2 40 140.0 0 5.0
> 1.29
> 2.5.60-cfq4 1 39 143.6 0 5.1
> 1.22
> 2.5.60-cfq8 2 40 140.0 0 5.0
> 1.29
> list_load:
> Kernel [runs] Time CPU% Loads
> LCPU% Ratio
> 2.5.60 2 35 157.1 0 8.6
> 1.13
> 2.5.60-cfq0 2 35 160.0 0 8.6
> 1.13
> 2.5.60-cfq16 2 35 160.0 0 14.3
> 1.13
> 2.5.60-cfq4 1 36 155.6 0 8.3
> 1.12
> 2.5.60-cfq8 2 35 160.0 0 11.4
> 1.13
> mem_load:
> Kernel [runs] Time CPU% Loads
> LCPU% Ratio
> 2.5.60 2 50 116.0 75 10.0
> 1.61
> 2.5.60-cfq0 2 57 101.8 78 8.8
> 1.84
> 2.5.60-cfq16 2 60 96.7 80 8.2
> 1.94
> 2.5.60-cfq4 1 52 111.5 76 9.4
> 1.62
> 2.5.60-cfq8 2 50 114.0 75 9.8
> 1.61
> dbench_load:
> Kernel [runs] Time CPU% Loads
> LCPU% Ratio
> 2.5.60 2 36 155.6 12693 27.8
> 1.16
> 2.5.60-cfq0 1 35 157.1 12013 28.6
> 1.13
> 2.5.60-cfq16 2 37 151.4 14356 32.4
> 1.19
> 2.5.60-cfq8 1 35 157.1 12174 31.4
> 1.13
>
> As I initialy expected, without having data to back
> it up, a non-zero
> quantum value helps. 16 was too much though, 4 looks
> a good choice. At
> least here.
They look pretty consistent with my results (does any
kernel hacker have a uniprocessor machine!?)
Impressive that changing a single setting without any
other tuning can almost get the same performance as
the "tuned up" current scheduler.
You can choose the loads when running contest by just
appending the loadnames:
contest no_load io_load xtar_load ctar_load
They all need at least one no_load to compare against.
The dbench issue has been fixed by the signal patch
from Linus.
Con
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This archive was generated by hypermail 2b29 : Sat Feb 15 2003 - 22:00:39 EST