Support for arm64 uncore performance counters?

[William Cohen]

Hi,

I noticed that the newer linux kernel provide uncore counters for arm64 processors much like the x86 processors:

https://www.kernel.org/doc/html/latest/admin-guide/perf/

Is there any thoughts/suggestions about adding uncore support for arm64? These events are visible to perf but not available in libpfm or papi.
For example I got access to RHEL8 cn9xx machine running a 4.18.0 kernel with the following processor:

processor : 1
BogoMIPS : 400.00
Features : fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics cpuid asimd
rdm
CPU implementer : 0x43
CPU architecture: 8
CPU variant : 0x1
CPU part : 0x0af
CPU revision : 0

The uncore events appear to be in the kernel

# perf list|grep uncore
uncore_dmc_0/cnt_cycles/ [Kernel PMU event]
uncore_dmc_0/data_transfers/ [Kernel PMU event]
uncore_dmc_0/read_txns/ [Kernel PMU event]
uncore_dmc_0/write_txns/ [Kernel PMU event]
uncore_dmc_1/cnt_cycles/ [Kernel PMU event]
uncore_dmc_1/data_transfers/ [Kernel PMU event]
uncore_dmc_1/read_txns/ [Kernel PMU event]
uncore_dmc_1/write_txns/ [Kernel PMU event]
uncore_l3c_0/evict_request/ [Kernel PMU event]
uncore_l3c_0/inv_hit/ [Kernel PMU event]
uncore_l3c_0/inv_nwrite_hit/ [Kernel PMU event]
uncore_l3c_0/inv_nwrite_request/ [Kernel PMU event]
uncore_l3c_0/inv_request/ [Kernel PMU event]
uncore_l3c_0/read_hit/ [Kernel PMU event]
uncore_l3c_0/read_request/ [Kernel PMU event]
uncore_l3c_0/writeback_request/ [Kernel PMU event]
uncore_l3c_1/evict_request/ [Kernel PMU event]
uncore_l3c_1/inv_hit/ [Kernel PMU event]
uncore_l3c_1/inv_nwrite_hit/ [Kernel PMU event]
uncore_l3c_1/inv_nwrite_request/ [Kernel PMU event]
uncore_l3c_1/inv_request/ [Kernel PMU event]
uncore_l3c_1/read_hit/ [Kernel PMU event]
uncore_l3c_1/read_request/ [Kernel PMU event]
uncore_l3c_1/writeback_request/ [Kernel PMU event]

-Will

[Vince Weaver]

On Mon, 22 Jul 2019, William Cohen wrote:

> I noticed that the newer linux kernel provide uncore counters for arm64 processors much like the x86 processors:
>
> https://www.kernel.org/doc/html/latest/admin-guide/perf/
>
> Is there any thoughts/suggestions about adding uncore support for arm64? These events are visible to perf but not available in libpfm or papi.
> For example I got access to RHEL8 cn9xx machine running a 4.18.0 kernel with the following processor:

In theory the perf_event_uncode component in PAPI shuld just-work assuming
the arm64 uncore events match the interface for the x86 ones.

PAPI however depends on libpfm4 support before the events will appear.

I don't think I currently have access to a sufficiently advanced arm64
machine that has uncore support.

Vince

[Steve Walk]

Hello,

It's my understanding that the changes for DMC and L3C events

have been merged to the mainline kernel and that the CCPI2 changes

are our for review.  I've reminded my management that papi/libpfm4

will need an update.  This should be on the workplan soon.

Is the official source for libpfm4 still over on bitbucket?  

Regards,

Steve Walk

Marvell

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