Re: Clarification on support of arm32 with kernel4.1 for oprofile 1.2.0

Does my hello.c work with the kernel rebuilt with CONFIG_HW_PERF_EVENTS=y ?

On Fri, 16 Feb 2018, Vinoth Natarajan wrote:
> Hello Michael,
> I have enabled the CONFIG_HW_PERF_EVENTS and tried oprofile -1.2.0 in the target.
> 
> Still the old error persists " ./operf
> Your kernel's Performance Events Subsystem does not support your processor type."
> 
> dmesg | grep -i -e perf -e pmu
> oprofile: no performance counters
> 
> In dmesg logs, it shows as no performance counters
> 
> Could you please share your feedback.
> 
> Thanks in Advance!!!
> 
> Thanks and Regards,
> Vinoth Natarajan.
> 
> On Thu, Feb 15, 2018 at 9:37 PM, Michael Petlan <[email protected]> wrote:
>       On Thu, 15 Feb 2018, Vinoth Natarajan wrote:
>       > Hello Michael,
>       > Thanks so much for the help.
>       >
>       > Cross compiled the hello.c with crosstools-arm-gcc-5.3-linux-4.1-glibc-2.22
>       > and tested the executable on the target(arm32)
>       >
>       > Received the following error
>       > " ./hello
>       > Error opening leader 1"
>       >
> 
>       This points to the kernel perf subsystem. It cannot even open a simple event.
>       Not an OProfile's fault.
> 
>       >
>       > Following are the kernel configs related to PERF in target
>       >
>       >  cat /tmp/test |grep PERF
>       >
>       > CONFIG_HAVE_PERF_EVENTS=y
>       > CONFIG_PERF_USE_VMALLOC=y
>       > CONFIG_PERF_EVENTS=y
>       > # CONFIG_DEBUG_PERF_USE_VMALLOC is not set
>       > CONFIG_HAVE_PERF_REGS=y
>       > CONFIG_HAVE_PERF_USER_STACK_DUMP=y
>       > # CONFIG_PCIEASPM_PERFORMANCE is not set
>       > # CONFIG_HW_PERF_EVENTS is not set
> 
>       I believe you need CONFIG_HW_PERF_EVENTS=y on ARM.
> 
>       > # CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE is not set
>       > # CONFIG_CPU_FREQ_GOV_PERFORMANCE is not set
>       > # CONFIG_CLS_U32_PERF is not set
>       >
>       > Could you please share your feedback on this.
> 
>       You may also try to grep for perf in logs:
> 
>       # dmesg | grep -i -e perf -e pmu
>       [    1.375699] hw perfevents: enabled with armv8_pmuv3_0 PMU driver, 5 counters available
>       [    1.403155] kvm [1]: GICV region size/alignment is unsafe, using trapping (reduced performance)
>       [    2.036285] xgene-pmu APMC0D5C:00: X-Gene PMU version 2
> 
>       ^^^ This is a log from the moment when my kernel identified and initialized
>       the PMU. You should see something like that too. Or better, after recompiling
>       your kernel with CONFIG_HW_PERF_EVENTS=y and booting, you should see something
>       like this (PMU-related logs). If there is some error in PMU init, you will see
>       it in the logs.
> 
>       I am afraid that without CONFIG_HW_PERF_EVENTS=y you cannot use the events.
> 
>       However, I don't guarantee that with CONFIG_HW_PERF_EVENTS=y it works. There
>       can be some firmware issues, ACPI issues, etc. I roughly remember some issue
>       when you'd need to boot with acpi=off to access the events, etc.
> 
>       Cheers,
>       Michael
> 
>       >
>       > Thanks in Advance!!!
>       >
>       > Thanks and Regards,
>       > Vinoth Natarajan.
>       >
>       [...]
> 
> 
> 
>

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