Re: [RFC][PATCH 0/7] sched: select_idle_siblings rewrite

[Chris Mason <clm@fb.com>]

On Mon, May 09, 2016 at 12:48:07PM +0200, Peter Zijlstra wrote:
> Hai,
> 
> here be a semi coherent patch series for the recent select_idle_siblings()
> tinkering. Happy benchmarking..

Thanks Peter,

I'll have some production numbers tomorrow, but based on schbench I'm
hoping it'll score better than my original.

You win on the pipe test (1.9MB/s vs 2.1MB/s) when a thread sibling is
pegged, and even when I double the think time on schbench, it holds up
well:

# Peter
# ./schbench -t 23 -m 2 -c 60000 -s 30000
Latency percentiles (usec)
	50.0000th: 50
	75.0000th: 60
	90.0000th: 69
	95.0000th: 73
	*99.0000th: 85
	99.5000th: 135
	99.9000th: 4012
	min=0, max=10873

# Mason
# ./schbench -t 23 -m 2 -c 60000 -s 30000
Latency percentiles (usec)
        50.0000th: 50
        75.0000th: 60
        90.0000th: 70
        95.0000th: 74
        *99.0000th: 83
        99.5000th: 88
        99.9000th: 118
        min=0, max=14770

# Mainline
# ./schbench -t 23 -m 2 -c 60000 -s 30000
Latency percentiles (usec)
        50.0000th: 47
        75.0000th: 60
        90.0000th: 70
        95.0000th: 79
        *99.0000th: 5400
        99.5000th: 10352
        99.9000th: 10992
        min=0, max=19642