[yocto] Build time data

Fri Apr 13 01:47:02 PDT 2012

Darren Hart wrote:
> One thing that comes to mind is the parallel settings, BB_NUMBER_THREADS
> and PARALLEL_MAKE. I noticed a negative impact if I increased these
> beyond 12 and 14 respectively. I tested this with bb-matrix
> (scripts/contrib/bb-perf/bb-matrix.sh). The script is a bit fickle, but
> can provide useful results and killer 3D surface plots of build time
> with BB and PM on the axis.

Very nice! I ran a batch overnight with permutations of 8,12,16,24,64 cores:

BB PM %e %S %U %P %c %w %R %F %M %x
8 8 2288.96 2611.37 10773.53 584% 810299 18460161 690464859 0 1715456 0
8 12 2198.40 2648.57 10846.28 613% 839750 18559413 690563187 0 1982864 0
8 16 2157.26 2672.79 10943.59 631% 898599 18487946 690761197 0 1715440 0
8 24 2125.15 2916.33 11199.27 664% 800009 18412764 690856116 0 1715440 0
8 64 2189.14 7084.14 12906.95 913% 1491503 18646891 699897733 0 1715440 0
12 8 2277.66 2625.82 10805.21 589% 691752 18596208 690998433 0 1715440 0
12 12 2194.04 2664.01 10934.65 619% 714997 18717017 691199925 0 1715440 0
12 16 2183.95 2736.33 11162.30 636% 1090270 18359128 690559327 0 1715440 0
12 24 2120.46 2907.63 11229.50 666% 829783 18644293 690729638 0 1715312 0
12 64 2171.58 6767.09 12822.86 902% 1524683 18634668 690904549 0 1867456 0
16 8 2294.59 2691.74 10813.69 588% 771621 18637582 686712129 0 1715344 0
16 12 2201.51 2704.54 11017.23 623% 753662 18590533 699231236 0 1715424 0
16 16 2154.54 2692.31 11023.28 636% 809586 18557781 691014487 0 1715440 0
16 24 2130.33 2932.18 11259.09 666% 905669 18531776 691082307 0 2030992 0
16 64 2184.01 6954.71 12922.39 910% 1467774 18800203 701770099 0 1715440 0
24 8 2284.88 2645.88 10854.89 590% 833061 18523938 691067170 0 1715328 0
24 12 2203.72 2696.96 11033.10 623% 931443 18457749 691187723 0 2016368 0
24 16 2176.02 2727.94 11113.33 636% 940044 18420200 690959670 0 1715440 0
24 24 2170.38 2938.80 11643.10 671% 1023328 18641215 686665448 15 1715440 0
24 64 2200.02 7188.60 12902.42 913% 1509158 18924772 690615091 66 1715440 0
64 8 2309.40 2702.33 10952.18 591% 753168 18687309 690927732 10 1867440 0
64 12 2230.80 2765.98 11131.22 622% 875495 18744802 691213524 28 1715216 0
64 16 2182.22 2786.22 11180.86 640% 881328 18724987 691020084 109 1768576 0
64 24 2136.20 3001.36 11238.81 666% 898320 18646384 691239254 46 1715312 0
64 64 2189.73 7154.10 12846.99 913% 1416830 18781801 690890798 41 1715424 0

What it shows is that BB_NUMBER_THREADS makes no difference at all in this range. As for PARALLEL_MAKE, it shows 24 is better than 16 but 64 is too high, incurring a massive scheduling penalty. I wonder if newer kernel versions have become more efficient. In hindsight, I should have included 32 and 48 cores in the test.

Unfortunately I was unable to produce plots with bb-matrix-plot.sh. It gave me pretty png files, but missing any plotted data:

# ../../poky/scripts/contrib/bb-perf/bb-matrix-plot.sh
         line 0: Number of grid points must be in [2:1000] - not changed!

  Warning: Single isoline (scan) is not enough for a pm3d plot.
           Hint: Missing blank lines in the data file? See 'help pm3d' and FAQ.
  Warning: Single isoline (scan) is not enough for a pm3d plot.
           Hint: Missing blank lines in the data file? See 'help pm3d' and FAQ.
  Warning: Single isoline (scan) is not enough for a pm3d plot.
           Hint: Missing blank lines in the data file? See 'help pm3d' and FAQ.
  Warning: Single isoline (scan) is not enough for a pm3d plot.
           Hint: Missing blank lines in the data file? See 'help pm3d' and FAQ.

Result: http://imgur.com/mfgWb

-- 
Björn