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4 Commits

Author SHA1 Message Date
Michal Suchanek
9899a56f1e powerpc: Fix build error in paravirt.h 
./arch/powerpc/include/asm/paravirt.h:83:44: error: implicit declaration
of function 'smp_processor_id'; did you mean 'raw_smp_processor_id'?

smp_processor_id is defined in linux/smp.h but it is not included.

The build error happens only when the patch is applied to 5.3 kernel but
it only works by chance in mainline.

Fixes: ca3f969dcb ("powerpc/paravirt: Use is_kvm_guest() in vcpu_is_preempted()")
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210120132838.15589-1-msuchanek@suse.de
 2021-01-31 22:35:49 +11:00
Srikar Dronamraju
ca3f969dcb powerpc/paravirt: Use is_kvm_guest() in vcpu_is_preempted() 
If its a shared LPAR but not a KVM guest, then see if the vCPU is
related to the calling vCPU. On PowerVM, only cores can be preempted.
So if one vCPU is a non-preempted state, we can decipher that all
other vCPUs sharing the same core are in non-preempted state.

Performance results:

  $ perf stat -r 5 -a perf bench sched pipe -l 10000000 (lesser time is better)

  powerpc/next
       35,107,951.20 msec cpu-clock                 #  255.898 CPUs utilized            ( +-  0.31% )
          23,655,348      context-switches          #    0.674 K/sec                    ( +-  3.72% )
              14,465      cpu-migrations            #    0.000 K/sec                    ( +-  5.37% )
              82,463      page-faults               #    0.002 K/sec                    ( +-  8.40% )
   1,127,182,328,206      cycles                    #    0.032 GHz                      ( +-  1.60% )  (66.67%)
      78,587,300,622      stalled-cycles-frontend   #    6.97% frontend cycles idle     ( +-  0.08% )  (50.01%)
     654,124,218,432      stalled-cycles-backend    #   58.03% backend cycles idle      ( +-  1.74% )  (50.01%)
     834,013,059,242      instructions              #    0.74  insn per cycle
                                                    #    0.78  stalled cycles per insn  ( +-  0.73% )  (66.67%)
     132,911,454,387      branches                  #    3.786 M/sec                    ( +-  0.59% )  (50.00%)
       2,890,882,143      branch-misses             #    2.18% of all branches          ( +-  0.46% )  (50.00%)

             137.195 +- 0.419 seconds time elapsed  ( +-  0.31% )

  powerpc/next + patchset
       29,981,702.64 msec cpu-clock                 #  255.881 CPUs utilized            ( +-  1.30% )
          40,162,456      context-switches          #    0.001 M/sec                    ( +-  0.01% )
               1,110      cpu-migrations            #    0.000 K/sec                    ( +-  5.20% )
              62,616      page-faults               #    0.002 K/sec                    ( +-  3.93% )
   1,430,030,626,037      cycles                    #    0.048 GHz                      ( +-  1.41% )  (66.67%)
      83,202,707,288      stalled-cycles-frontend   #    5.82% frontend cycles idle     ( +-  0.75% )  (50.01%)
     744,556,088,520      stalled-cycles-backend    #   52.07% backend cycles idle      ( +-  1.39% )  (50.01%)
     940,138,418,674      instructions              #    0.66  insn per cycle
                                                    #    0.79  stalled cycles per insn  ( +-  0.51% )  (66.67%)
     146,452,852,283      branches                  #    4.885 M/sec                    ( +-  0.80% )  (50.00%)
       3,237,743,996      branch-misses             #    2.21% of all branches          ( +-  1.18% )  (50.01%)

              117.17 +- 1.52 seconds time elapsed  ( +-  1.30% )

This is around 14.6% improvement in performance.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Waiman Long <longman@redhat.com>
[mpe: Fold in performance results from cover letter]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201202050456.164005-5-srikar@linux.vnet.ibm.com
 2020-12-04 01:01:22 +11:00
Nicholas Piggin
20c0e8269e powerpc/pseries: Implement paravirt qspinlocks for SPLPAR 
This implements the generic paravirt qspinlocks using H_PROD and
H_CONFER to kick and wait.

This uses an un-directed yield to any CPU rather than the directed
yield to a pre-empted lock holder that paravirtualised simple
spinlocks use, that requires no kick hcall. This is something that
could be investigated and improved in future.

Performance results can be found in the commit which added queued
spinlocks.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200724131423.1362108-5-npiggin@gmail.com
 2020-07-27 00:01:29 +10:00
Nicholas Piggin
20d444d06f powerpc/pseries: Move some PAPR paravirt functions to their own file 
These functions will be used by the queued spinlock implementation,
and may be useful elsewhere too, so move them out of spinlock.h.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200724131423.1362108-2-npiggin@gmail.com
 2020-07-26 23:34:26 +10:00