Re: Hackbench pipes regression bisected to PSI

[Johannes Weiner]

On Mon, Nov 26, 2018 at 11:29:26PM +0000, Mel Gorman wrote:
> The following is a comparision using CONFIG_PSI=n as a baseline against
> your patch and a vanilla kernel
> 
>                          4.20.0-rc4             4.20.0-rc4             4.20.0-rc4
>                 kconfigdisable-v1r1                vanilla        psidisable-v1r1
> Amean     1       1.3100 (   0.00%)      1.3923 (  -6.28%)      1.3427 (  -2.49%)
> Amean     3       3.8860 (   0.00%)      4.1230 *  -6.10%*      3.8860 (  -0.00%)
> Amean     5       6.8847 (   0.00%)      8.0390 * -16.77%*      6.7727 (   1.63%)
> Amean     7       9.9310 (   0.00%)     10.8367 *  -9.12%*      9.9910 (  -0.60%)
> Amean     12     16.6577 (   0.00%)     18.2363 *  -9.48%*     17.1083 (  -2.71%)
> Amean     18     26.5133 (   0.00%)     27.8833 *  -5.17%*     25.7663 (   2.82%)
> Amean     24     34.3003 (   0.00%)     34.6830 (  -1.12%)     32.0450 (   6.58%)
> Amean     30     40.0063 (   0.00%)     40.5800 (  -1.43%)     41.5087 (  -3.76%)
> Amean     32     40.1407 (   0.00%)     41.2273 (  -2.71%)     39.9417 (   0.50%)
> 
> It's showing that the vanilla kernel takes a hit (as the bisection
> indicated it would) and that disabling PSI by default is reasonably
> close in terms of performance for this particular workload on this
> particular machine so;
> 
> Tested-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>

Thanks for testing it. Let's add these results to the changelog:

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