Re: [RFC v2 00/34] SLUB: reduce irq disabled scope and make it RT compatible

[Mike Galbraith]

On Sun, 2021-07-18 at 10:29 +0200, Mike Galbraith wrote:
> On Sun, 2021-07-18 at 09:41 +0200, Vlastimil Babka wrote:
> > On 7/3/21 9:24 AM, Mike Galbraith wrote:
> > > On Fri, 2021-07-02 at 20:29 +0200, Sebastian Andrzej Siewior
> > > wrote:
> > > > I replaced my slub changes with slub-local-lock-v2r3.
> > > > I haven't seen any complains from lockdep or so which is good.
> > > > Then I
> > > > did this with RT enabled (and no debug):
> > >
> > > Below is some raw hackbench data from my little i4790 desktop
> > > box.  It
> > > says we'll definitely still want list_lock to be raw.
> >
> > Hi Mike, thanks a lot for the testing, sorry for late reply.
> >
> > Did you try, instead of raw list_lock, not applying the last, local
> > lock patch, as I suggested in reply to bigeasy?
>
> No, but I suppose I can give that a go.

The kernel has of course moved forward, so measure 'em again, but
starting before replacing 5.12-rt patches with slub-local-lock-v2r3.

box is old i4790 desktop
perf stat -r10 hackbench -s4096 -l500
full warmup, record, repeat twice for elapsed

Config has only SLUB+SLUB_DEBUG, as originally measured.

5.14.0.g79e92006-tip-rt (5.12-rt, 5.13-rt didn't exist when first measured)
          7,984.52 msec task-clock                #    7.565 CPUs utilized            ( +-  0.66% )
           353,566      context-switches          #   44.281 K/sec                    ( +-  2.77% )
            37,685      cpu-migrations            #    4.720 K/sec                    ( +-  6.37% )
            12,939      page-faults               #    1.620 K/sec                    ( +-  0.67% )
    29,901,079,227      cycles                    #    3.745 GHz                      ( +-  0.71% )
    14,550,797,818      instructions              #    0.49  insn per cycle           ( +-  0.47% )
     3,056,685,643      branches                  #  382.826 M/sec                    ( +-  0.51% )
         9,598,083      branch-misses             #    0.31% of all branches          ( +-  2.11% )

           1.05542 +- 0.00409 seconds time elapsed  ( +-  0.39% )
           1.05990 +- 0.00244 seconds time elapsed  ( +-  0.23% ) (repeat)
           1.05367 +- 0.00303 seconds time elapsed  ( +-  0.29% ) (repeat)

5.14.0.g79e92006-tip-rt +slub-local-lock-v2r3 -0034-mm-slub-convert-kmem_cpu_slab-protection-to-local_lock.patch
          6,899.35 msec task-clock                #    5.637 CPUs utilized            ( +-  0.53% )
           420,304      context-switches          #   60.919 K/sec                    ( +-  2.83% )
           187,130      cpu-migrations            #   27.123 K/sec                    ( +-  1.81% )
            13,206      page-faults               #    1.914 K/sec                    ( +-  0.96% )
    25,110,362,933      cycles                    #    3.640 GHz                      ( +-  0.49% )
    15,853,643,635      instructions              #    0.63  insn per cycle           ( +-  0.64% )
     3,366,261,524      branches                  #  487.910 M/sec                    ( +-  0.70% )
        14,839,618      branch-misses             #    0.44% of all branches          ( +-  2.01% )

           1.22390 +- 0.00744 seconds time elapsed  ( +-  0.61% )
           1.21813 +- 0.00907 seconds time elapsed  ( +-  0.74% ) (repeat)
           1.22097 +- 0.00952 seconds time elapsed  ( +-  0.78% ) (repeat)

repeat of above with raw list_lock
          8,072.62 msec task-clock                #    7.605 CPUs utilized            ( +-  0.49% )
           359,514      context-switches          #   44.535 K/sec                    ( +-  4.95% )
            35,285      cpu-migrations            #    4.371 K/sec                    ( +-  5.82% )
            13,503      page-faults               #    1.673 K/sec                    ( +-  0.96% )
    30,247,989,681      cycles                    #    3.747 GHz                      ( +-  0.52% )
    14,580,011,391      instructions              #    0.48  insn per cycle           ( +-  0.81% )
     3,063,743,405      branches                  #  379.523 M/sec                    ( +-  0.85% )
         8,907,160      branch-misses             #    0.29% of all branches          ( +-  3.99% )

           1.06150 +- 0.00427 seconds time elapsed  ( +-  0.40% )
           1.05041 +- 0.00176 seconds time elapsed  ( +-  0.17% ) (repeat)
           1.06086 +- 0.00237 seconds time elapsed  ( +-  0.22% ) (repeat)

5.14.0.g79e92006-rt3-tip-rt +slub-local-lock-v2r3 full set
          7,598.44 msec task-clock                #    5.813 CPUs utilized            ( +-  0.85% )
           488,161      context-switches          #   64.245 K/sec                    ( +-  4.29% )
           196,866      cpu-migrations            #   25.909 K/sec                    ( +-  1.49% )
            13,042      page-faults               #    1.716 K/sec                    ( +-  0.73% )
    27,695,116,746      cycles                    #    3.645 GHz                      ( +-  0.79% )
    18,423,934,168      instructions              #    0.67  insn per cycle           ( +-  0.88% )
     3,969,540,695      branches                  #  522.415 M/sec                    ( +-  0.92% )
        15,493,482      branch-misses             #    0.39% of all branches          ( +-  2.15% )

           1.30709 +- 0.00890 seconds time elapsed  ( +-  0.68% )
           1.3205 +- 0.0134 seconds time elapsed  ( +-  1.02% ) (repeat)
           1.3083 +- 0.0132 seconds time elapsed  ( +-  1.01% ) (repeat)