Re: [PATCH 0/2] perf: riscv: Preliminary Perf Event Support on RISC-V

Re: [PATCH 0/2] perf: riscv: Preliminary Perf Event Support on RISC-V

[Alan Kao]

On Tue, Apr 03, 2018 at 03:45:17PM -0700, Palmer Dabbelt wrote:
> On Tue, 03 Apr 2018 07:29:02 PDT (-0700), alankao@andestech.com wrote:
> >On Mon, Apr 02, 2018 at 08:15:44PM -0700, Palmer Dabbelt wrote:
> >>On Mon, 02 Apr 2018 05:31:22 PDT (-0700), alankao@andestech.com 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 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                  |  12 +
> >>> arch/riscv/include/asm/perf_event.h |  76 +++++-
> >>> arch/riscv/kernel/Makefile          |   1 +
> >>> arch/riscv/kernel/perf_event.c      | 468 ++++++++++++++++++++++++++++++++++++
> >>> 5 files changed, 802 insertions(+), 4 deletions(-)
> >>> create mode 100644 Documentation/riscv/pmu.txt
> >>> create mode 100644 arch/riscv/kernel/perf_event.c
> >>
> >>I'm having some trouble pulling this into my tree.  I think you might have
> >>another patch floating around somewhere, as I don't have any
> >>arch/riscv/include/asm/perf_event.h right now.
> >>
> >>Do you mind rebasing this on top of linux-4.16 so I can look properly?
> >>
> >>Thanks!
> >
> >Sorry for the inconvenience, but this patch was based on Alex's patch at
> >https://github.com/riscv/riscv-linux/pull/124/files.  I thought that one
> >had already been picked into your tree.
> >
> >Any ideas?
> 
> Thanks, it applies on top of that.  I'm going to play around with this a
> bit, but it looks generally good.

Note that to make it work better when wraparound occurs, you should change the
value of *.counter_width* into the width of real hardware counters.  This is
because this patch does not handle wraparound checking, so using a wider
bit mask may sometimes report a extremely large number.

Ideally this should be done by adding a Kconfig option called 
"Hifive Unleashed PMU" which automatically sets the width an reuses most of the
baseline codes.  What do you think about this?

Thanks.

Re: [PATCH 0/2] perf: riscv: Preliminary Perf Event Support on RISC-V

[Palmer Dabbelt]

On Wed, 04 Apr 2018 22:02:29 PDT (-0700), alankao@andestech.com wrote:
> On Tue, Apr 03, 2018 at 03:45:17PM -0700, Palmer Dabbelt wrote:
>> On Tue, 03 Apr 2018 07:29:02 PDT (-0700), alankao@andestech.com wrote:
>> >On Mon, Apr 02, 2018 at 08:15:44PM -0700, Palmer Dabbelt wrote:
>> >>On Mon, 02 Apr 2018 05:31:22 PDT (-0700), alankao@andestech.com 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 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                  |  12 +
>> >>> arch/riscv/include/asm/perf_event.h |  76 +++++-
>> >>> arch/riscv/kernel/Makefile          |   1 +
>> >>> arch/riscv/kernel/perf_event.c      | 468 ++++++++++++++++++++++++++++++++++++
>> >>> 5 files changed, 802 insertions(+), 4 deletions(-)
>> >>> create mode 100644 Documentation/riscv/pmu.txt
>> >>> create mode 100644 arch/riscv/kernel/perf_event.c
>> >>
>> >>I'm having some trouble pulling this into my tree.  I think you might have
>> >>another patch floating around somewhere, as I don't have any
>> >>arch/riscv/include/asm/perf_event.h right now.
>> >>
>> >>Do you mind rebasing this on top of linux-4.16 so I can look properly?
>> >>
>> >>Thanks!
>> >
>> >Sorry for the inconvenience, but this patch was based on Alex's patch at
>> >https://github.com/riscv/riscv-linux/pull/124/files.  I thought that one
>> >had already been picked into your tree.
>> >
>> >Any ideas?
>>
>> Thanks, it applies on top of that.  I'm going to play around with this a
>> bit, but it looks generally good.
>
> Note that to make it work better when wraparound occurs, you should change the
> value of *.counter_width* into the width of real hardware counters.  This is
> because this patch does not handle wraparound checking, so using a wider
> bit mask may sometimes report a extremely large number.
>
> Ideally this should be done by adding a Kconfig option called
> "Hifive Unleashed PMU" which automatically sets the width an reuses most of the
> baseline codes.  What do you think about this?

We're working through this now :)

Re: [PATCH 0/2] perf: riscv: Preliminary Perf Event Support on RISC-V

[Palmer Dabbelt]

On Mon, 02 Apr 2018 05:31:22 PDT (-0700), alankao@andestech.com 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 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                  |  12 +
>  arch/riscv/include/asm/perf_event.h |  76 +++++-
>  arch/riscv/kernel/Makefile          |   1 +
>  arch/riscv/kernel/perf_event.c      | 468 ++++++++++++++++++++++++++++++++++++
>  5 files changed, 802 insertions(+), 4 deletions(-)
>  create mode 100644 Documentation/riscv/pmu.txt
>  create mode 100644 arch/riscv/kernel/perf_event.c

I'm having some trouble pulling this into my tree.  I think you might have 
another patch floating around somewhere, as I don't have any 
arch/riscv/include/asm/perf_event.h right now.

Do you mind rebasing this on top of linux-4.16 so I can look properly?

Thanks!

[PATCH 0/2] perf: riscv: Preliminary Perf Event Support on RISC-V

[Alan Kao]

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 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                  |  12 +
 arch/riscv/include/asm/perf_event.h |  76 +++++-
 arch/riscv/kernel/Makefile          |   1 +
 arch/riscv/kernel/perf_event.c      | 468 ++++++++++++++++++++++++++++++++++++
 5 files changed, 802 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/riscv/pmu.txt
 create mode 100644 arch/riscv/kernel/perf_event.c

-- 
2.16.2

[PATCH 0/2] perf: riscv: Preliminary Perf Event Support on RISC-V

[Alan Kao]

This implements the baseline PMU for RISC-V platforms.

To ease the future PMU portings, a guide is also written, containing
perf concepts, arch porting practices and some hints.

Alan Kao (2):
  perf: riscv: preliminary RISC-V support
  perf: riscv: Add Document for Future Porting Guide

 Documentation/riscv/pmu.txt         | 250 +++++++++++++++++++
 arch/riscv/Kconfig                  |  12 +
 arch/riscv/include/asm/perf_event.h |  76 +++++-
 arch/riscv/kernel/Makefile          |   1 +
 arch/riscv/kernel/perf_event.c      | 469 ++++++++++++++++++++++++++++++++++++
 5 files changed, 804 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/riscv/pmu.txt
 create mode 100644 arch/riscv/kernel/perf_event.c

-- 
2.16.2