Re: [PATCH V12 2/4] drivers/perf: imx_ddr: Add ddr performance counter support

[Zhi Li <lznuaa@gmail.com>]

On Thu, Jun 13, 2019 at 12:44 PM Will Deacon <will.deacon@arm.com> wrote:
>
> On Thu, Jun 13, 2019 at 12:04:37PM -0500, Zhi Li wrote:
> > On Thu, Jun 13, 2019 at 6:23 AM Will Deacon <will.deacon@arm.com> wrote:
> > >
> > > On Wed, May 01, 2019 at 06:43:29PM +0000, Frank Li wrote:
> > > > Add ddr performance monitor support for iMX8QXP
> > > >
> > > > There are 4 counters for ddr perfomance events.
> > > > counter 0 is dedicated for cycles.
> > > > you choose any up to 3 no cycles events.
> > > >
> > > > for example:
> > > >
> > > > perf stat -a -e imx8_ddr0/read-cycles/,imx8_ddr0/write-cycles/,imx8_ddr0/precharge/ ls
> > > > perf stat -a -e imx8_ddr0/cycles/,imx8_ddr0/read-access/,imx8_ddr0/write-access/ ls
> > >
> > > I've pushed patches 1, 2 and 4 out with some minor tweaks to:
> > >
> > > https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=for-next/perf
> > >
> > > I'll leave the actual .dts change to go via the soc tree, since last time
> > > I took one of those it just resulted in conflicts.
> > >
> > > Frank, Andrey: Please could you try to run the perf fuzzer on this before
> > > it lands in mainline? It has a good track record of finding nasty PMU driver
> > > bugs, but it obviously requires access to hardware which implements the PMU:
> > >
> > > http://web.eece.maine.edu/~vweaver/projects/perf_events/fuzzer/
> >
> > Okay, how long should be run generally?
> > I need make sure it can pass without my patches at our platform.
>
> As you long as you can really, but if it survives a few hours that's usually
> a good sign. Overnight is even better.

Base on commit f2c7c76c5d0a443053e94adb9f0918fa2fb85c3a
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun Jun 2 13:55:33 2019 -0700

    Linux 5.2-rc3

RCU report problem:

[ 6048.741784] rcu: INFO: rcu_preempt self-detected stall on CPU
[ 6048.747550] rcu:     1-....: (5249 ticks this GP)
idle=c5a/1/0x4000000000000004 softirq=503121/503121 fqs=2425
[ 6048.757384]  (t=5253 jiffies g=1416105 q=117)
[ 6048.761745] Task dump for CPU 1:
[ 6048.764977] perf_fuzzer     R  running task        0 32520    426 0x00000202
[ 6048.772030] Call trace:
[ 6048.774493]  dump_backtrace+0x0/0x130
[ 6048.778159]  show_stack+0x14/0x20
[ 6048.781477]  sched_show_task+0x108/0x138
[ 6048.785401]  dump_cpu_task+0x40/0x4c
[ 6048.788983]  rcu_dump_cpu_stacks+0x94/0xd0
[ 6048.793082]  rcu_sched_clock_irq+0x5e0/0x918
[ 6048.797357]  update_process_times+0x2c/0x70
[ 6048.801545]  tick_sched_handle.isra.6+0x3c/0x50
[ 6048.806076]  tick_sched_timer+0x48/0x98
[ 6048.809918]  __hrtimer_run_queues+0x118/0x1a8
[ 6048.814277]  hrtimer_interrupt+0xe4/0x238
[ 6048.818296]  arch_timer_handler_phys+0x2c/0x38
[ 6048.822743]  handle_percpu_devid_irq+0x80/0x140
[ 6048.827277]  generic_handle_irq+0x24/0x38

Only armv8_pmuv3 and basic perf event enabled.
perf list

List of pre-defined events (to be used in -e):

  branch-instructions OR branches                    [Hardware event]
  branch-misses                                      [Hardware event]
  bus-cycles                                         [Hardware event]
  cache-misses                                       [Hardware event]
  cache-references                                   [Hardware event]
  cpu-cycles OR cycles                               [Hardware event]
  instructions                                       [Hardware event]

  alignment-faults                                   [Software event]
  bpf-output                                         [Software event]
  context-switches OR cs                             [Software event]
  cpu-clock                                          [Software event]
  cpu-migrations OR migrations                       [Software event]
  dummy                                              [Software event]
  emulation-faults                                   [Software event]
  major-faults                                       [Software event]
  minor-faults                                       [Software event]
  page-faults OR faults                              [Software event]
  task-clock                                         [Software event]

  L1-dcache-load-misses                              [Hardware cache event]
  L1-dcache-loads                                    [Hardware cache event]
  L1-icache-load-misses                              [Hardware cache event]
  L1-icache-loads                                    [Hardware cache event]
  branch-load-misses                                 [Hardware cache event]
  branch-loads                                       [Hardware cache event]
  dTLB-load-misses                                   [Hardware cache event]
  iTLB-load-misses                                   [Hardware cache event]

  armv8_pmuv3/br_immed_retired/                      [Kernel PMU event]
  armv8_pmuv3/br_mis_pred/                           [Kernel PMU event]
 ****8

>
> Will

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