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SubjectRe: [PATCH v5 0/2] perf: riscv: Preliminary Perf Event Support on RISC-V
Date
On 4/19/18 4:28 PM, Alan Kao wrote:
> This implements the baseline PMU for RISC-V platforms.
>
> To ease future PMU portings, a guide is also written, containing
> perf concepts, arch porting practices and some hints.
>
> Changes in v5:
> - Fix patch errors from checkpatch.pl.
>
> Changes in v4:
> - Fix several compilation errors. Sorry for that.
> - Raise a warning in the write_counter body.
>
> Changes in v3:
> - Fix typos in the document.
> - Change the initialization routine from statically assigning PMU to
> device-tree-based methods, and set default to the PMU proposed in
> this patch.
>
> Changes in v2:
> - Fix the bug reported by Alex, which was caused by not sufficient
> initialization. Check https://lkml.org/lkml/2018/3/31/251 for the
> discussion.
>
> Alan Kao (2):
> perf: riscv: preliminary RISC-V support
> perf: riscv: Add Document for Future Porting Guide
>
> Documentation/riscv/pmu.txt | 249 ++++++++++++++
> arch/riscv/Kconfig | 13 +
> arch/riscv/include/asm/perf_event.h | 79 ++++-
> arch/riscv/kernel/Makefile | 1 +
> arch/riscv/kernel/perf_event.c | 485 ++++++++++++++++++++++++++++
> 5 files changed, 823 insertions(+), 4 deletions(-)
> create mode 100644 Documentation/riscv/pmu.txt
> create mode 100644 arch/riscv/kernel/perf_event.c
>
Most of the perf tests either pass or fail because of unsupported
event/trace point which is fine.

However, I got an rcu-stall for the test "47: Event times".
# ./perf test -v 47
47: Event times :
--- start ---
test child forked, pid 2774
attaching to spawned child, enable on exec
OK : ena 2243000, run 2243000
attaching to current thread as enabled
OK : ena 19000, run 19000
attaching to current thread as disabled
OK : ena 5000, run 5000
attaching to CPU 0 as enabled
[ 1001.466578] INFO: rcu_sched self-detected stall on CPU
[ 1001.470947] 4-....: (29999 ticks this GP) idle=5fa/140000000000001/0
softirq=19762/19762 fqs=14602
[ 1001.480053] (t=30001 jiffies g=3471 c=3470 q=125)
[ 1001.484917] Task dump for CPU 4:
[ 1001.488129] perf R running task 0 2774 2773
0x00000008
[ 1001.495161] Call Trace:
[ 1001.497606] [<000000006a3d4f87>] walk_stackframe+0x0/0xc0
[ 1001.502980] [<000000004b4b0780>] show_stack+0x3c/0x46
[ 1001.508024] [<0000000060c96ab8>] sched_show_task+0xd0/0x122
[ 1001.513573] [<000000007d8bd54e>] dump_cpu_task+0x50/0x5a
[ 1001.518870] [<0000000053990e11>] rcu_dump_cpu_stacks+0x98/0xd2
[ 1001.524685] [<00000000fe94c593>] rcu_check_callbacks+0x614/0x822
[ 1001.530680] [<0000000057688dd3>] update_process_times+0x38/0x6a
[ 1001.536585] [<0000000063a96de0>] tick_periodic+0x58/0xd8
[ 1001.541876] [<0000000013d712f1>] tick_handle_periodic+0x2e/0x7c
[ 1001.547780] [<000000009e2ef428>] riscv_timer_interrupt+0x34/0x3c
[ 1001.553774] [<00000000ff6b1f18>] riscv_intc_irq+0xbc/0xe0
[ 1001.559153] [<00000000c8614c3b>] ret_from_exception+0x0/0xc

It is quite possible that we don't support some dependency
infrastructure. I am looking into it.

Regards,
Atish




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