Re: [PATCH 3/3] slub: build detached freelist with look-ahead

[Jesper Dangaard Brouer <brouer@redhat.com>]

On Tue, 21 Jul 2015 08:50:36 -0500 (CDT)
Christoph Lameter <cl@linux.com> wrote:

> On Mon, 20 Jul 2015, Jesper Dangaard Brouer wrote:
> 
> > Yes, I think it is merged... how do I turn off merging?
> 
> linux/Documentation/kernel-parameters.txt
> 
>         slab_nomerge    [MM]
>                         Disable merging of slabs with similar size. May be
>                         necessary if there is some reason to distinguish
>                         allocs to different slabs. Debug options disable
>                         merging on their own.
>                         For more information see Documentation/vm/slub.txt.

I was hoping I could define this per slub runtime.  Any chance this
would be made possible?

Setting boot param "slab_nomerge" made my benchmarking VERY stable
between runs (obj size 256).


Run01: slab_nomerge
1 - 63 cycles(tsc) 15.927 ns -  46 cycles(tsc) 11.707 ns
2 - 56 cycles(tsc) 14.185 ns -  28 cycles(tsc) 7.129 ns
3 - 54 cycles(tsc) 13.588 ns -  23 cycles(tsc) 5.762 ns
4 - 53 cycles(tsc) 13.291 ns -  20 cycles(tsc) 5.085 ns
8 - 51 cycles(tsc) 12.918 ns -  19 cycles(tsc) 4.886 ns
16 - 50 cycles(tsc) 12.607 ns -  19 cycles(tsc) 4.858 ns
30 - 51 cycles(tsc) 12.759 ns -  19 cycles(tsc) 4.980 ns
32 - 51 cycles(tsc) 12.930 ns -  19 cycles(tsc) 4.975 ns
34 - 93 cycles(tsc) 23.410 ns -  27 cycles(tsc) 6.924 ns
48 - 80 cycles(tsc) 20.193 ns -  25 cycles(tsc) 6.279 ns
64 - 73 cycles(tsc) 18.322 ns -  23 cycles(tsc) 5.939 ns
128 - 88 cycles(tsc) 22.083 ns -  29 cycles(tsc) 7.413 ns
158 - 97 cycles(tsc) 24.274 ns -  34 cycles(tsc) 8.696 ns
250 - 102 cycles(tsc) 25.556 ns -  40 cycles(tsc) 10.100 ns

Run02: slab_nomerge
1 - 63 cycles(tsc) 15.879 ns -  46 cycles(tsc) 11.701 ns
2 - 56 cycles(tsc) 14.222 ns -  28 cycles(tsc) 7.140 ns
3 - 54 cycles(tsc) 13.586 ns -  23 cycles(tsc) 5.783 ns
4 - 53 cycles(tsc) 13.339 ns -  20 cycles(tsc) 5.095 ns
8 - 51 cycles(tsc) 12.899 ns -  19 cycles(tsc) 4.905 ns
16 - 50 cycles(tsc) 12.624 ns -  19 cycles(tsc) 4.853 ns
30 - 51 cycles(tsc) 12.781 ns -  19 cycles(tsc) 4.984 ns
32 - 51 cycles(tsc) 12.933 ns -  19 cycles(tsc) 4.997 ns
34 - 93 cycles(tsc) 23.421 ns -  27 cycles(tsc) 6.909 ns
48 - 80 cycles(tsc) 20.241 ns -  25 cycles(tsc) 6.267 ns
64 - 73 cycles(tsc) 18.346 ns -  23 cycles(tsc) 5.947 ns
128 - 88 cycles(tsc) 22.192 ns -  29 cycles(tsc) 7.415 ns
158 - 97 cycles(tsc) 24.358 ns -  34 cycles(tsc) 8.693 ns
250 - 102 cycles(tsc) 25.597 ns -  40 cycles(tsc) 10.144 ns

Run03: slab_nomerge
1 - 63 cycles(tsc) 15.897 ns -  46 cycles(tsc) 11.685 ns
2 - 56 cycles(tsc) 14.178 ns -  28 cycles(tsc) 7.132 ns
3 - 54 cycles(tsc) 13.590 ns -  23 cycles(tsc) 5.774 ns
4 - 53 cycles(tsc) 13.314 ns -  20 cycles(tsc) 5.092 ns
8 - 51 cycles(tsc) 12.872 ns -  19 cycles(tsc) 4.886 ns
16 - 50 cycles(tsc) 12.603 ns -  19 cycles(tsc) 4.840 ns
30 - 50 cycles(tsc) 12.750 ns -  19 cycles(tsc) 4.966 ns
32 - 51 cycles(tsc) 12.910 ns -  19 cycles(tsc) 4.977 ns
34 - 93 cycles(tsc) 23.372 ns -  27 cycles(tsc) 6.929 ns
48 - 80 cycles(tsc) 20.205 ns -  25 cycles(tsc) 6.276 ns
64 - 73 cycles(tsc) 18.292 ns -  23 cycles(tsc) 5.929 ns
128 - 90 cycles(tsc) 22.516 ns -  29 cycles(tsc) 7.425 ns
158 - 99 cycles(tsc) 24.825 ns -  34 cycles(tsc) 8.668 ns
250 - 102 cycles(tsc) 25.652 ns -  40 cycles(tsc) 10.129 ns


-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Sr. Network Kernel Developer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer

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