Re: [PATCH 03/19] sched/numa: Simplify load_too_imbalanced

[Mel Gorman]

On Mon, Jun 04, 2018 at 03:30:12PM +0530, Srikar Dronamraju wrote:
> Currently load_too_imbalance() cares about the slope of imbalance.
> It doesn't care of the direction of the imbalance.
> 
> However this may not work if nodes that are being compared have
> dissimilar capacities. Few nodes might have more cores than other nodes
> in the system. Also unlike traditional load balance at a NUMA sched
> domain, multiple requests to migrate from the same source node to same
> destination node may run in parallel. This can cause huge load
> imbalance. This is specially true on a larger machines with either large
> cores per node or more number of nodes in the system. Hence allow
> move/swap only if the imbalance is going to reduce.
> 
> Testcase       Time:         Min         Max         Avg      StdDev
> numa01.sh      Real:      516.14      892.41      739.84      151.32
> numa01.sh       Sys:      153.16      192.99      177.70       14.58
> numa01.sh      User:    39821.04    69528.92    57193.87    10989.48
> numa02.sh      Real:       60.91       62.35       61.58        0.63
> numa02.sh       Sys:       16.47       26.16       21.20        3.85
> numa02.sh      User:     5227.58     5309.61     5265.17       31.04
> numa03.sh      Real:      739.07      917.73      795.75       64.45
> numa03.sh       Sys:       94.46      136.08      109.48       14.58
> numa03.sh      User:    57478.56    72014.09    61764.48     5343.69
> numa04.sh      Real:      442.61      715.43      530.31       96.12
> numa04.sh       Sys:      224.90      348.63      285.61       48.83
> numa04.sh      User:    35836.84    47522.47    40235.41     3985.26
> numa05.sh      Real:      386.13      489.17      434.94       43.59
> numa05.sh       Sys:      144.29      438.56      278.80      105.78
> numa05.sh      User:    33255.86    36890.82    34879.31     1641.98
> 
> Testcase       Time:         Min         Max         Avg      StdDev 	 %Change
> numa01.sh      Real:      435.78      653.81      534.58       83.20 	 38.39%
> numa01.sh       Sys:      121.93      187.18      145.90       23.47 	 21.79%
> numa01.sh      User:    37082.81    51402.80    43647.60     5409.75 	 31.03%
> numa02.sh      Real:       60.64       61.63       61.19        0.40 	 0.637%
> numa02.sh       Sys:       14.72       25.68       19.06        4.03 	 11.22%
> numa02.sh      User:     5210.95     5266.69     5233.30       20.82 	 0.608%
> numa03.sh      Real:      746.51      808.24      780.36       23.88 	 1.972%
> numa03.sh       Sys:       97.26      108.48      105.07        4.28 	 4.197%
> numa03.sh      User:    58956.30    61397.05    60162.95     1050.82 	 2.661%
> numa04.sh      Real:      465.97      519.27      484.81       19.62 	 9.385%
> numa04.sh       Sys:      304.43      359.08      334.68       20.64 	 -14.6%
> numa04.sh      User:    37544.16    41186.15    39262.44     1314.91 	 2.478%
> numa05.sh      Real:      411.57      457.20      433.29       16.58 	 0.380%
> numa05.sh       Sys:      230.05      435.48      339.95       67.58 	 -17.9%
> numa05.sh      User:    33325.54    36896.31    35637.84     1222.64 	 -2.12%
> 
> Signed-off-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>

Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>

-- 
Mel Gorman
SUSE Labs