linux-kernel - Re: perf record doesn't work on rtd129x SoC

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Message-ID: <f90748d0-8112-3aa8-0c88-e35a8d6e72d3@suse.de>
Date:   Wed, 4 Dec 2019 08:28:26 +0100
From:   Andreas Färber <afaerber@...e.de>
To:     Wang YanQing <udknight@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-realtek-soc@...ts.infradead.org,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Mark Rutland <mark.rutland@....com>,
        Will Deacon <will.deacon@....com>
Subject: Re: perf record doesn't work on rtd129x SoC

Hi YanQing,

+ LAKML + Mark + Will

Am 04.12.19 um 05:55 schrieb Wang YanQing:
> I use "perf record" to debug performance issue on RTD1296 SOC, it does't work, but
> the "perf stat" is ok!

Thanks for the report - which board, branch and (base) tag are you
testing against? And are you building perf yourself from kernel sources,
or are you using some distro package?

I only have Busybox in my initrd on DS418; I have not tested perf.

> After some dig in the kernel, I find the reason is no pmu overflow interrupt, I think
> below pmu configuration isn't right for RTD1296:
> "
>         arm_pmu: arm-pmu {
>                 compatible = "arm,cortex-a53-pmu";
>                 interrupts = <GIC_SPI 48 IRQ_TYPE_LEVEL_HIGH>;
>         };
> "
> 
> We need 4 PMU SPI for RTD1296 (4 cores), and I guess the 48 isn't right too.

Note that above rtd129x.dtsi snippet is not complete. See rtd1296.dtsi:

&arm_pmu {
	interrupt-affinity = <&cpu0>, <&cpu1>, <&cpu2>, <&cpu3>;
};

48 and high/4 match what I see in the latest BSP:

https://github.com/BPI-SINOVOIP/BPI-M4-bsp/blob/master/linux-rtk/arch/arm64/boot/dts/realtek/rtd129x/rtd-1296.dtsi#L116

> Any suggestion is welcome.
> 
> Thanks!

The only difference I see is "arm,cortex-a53-pmu" vs. "arm,armv8-pmuv3".
By my reading of arch/arm64/kernel/perf_event.c the only difference
between the two should be the name and an extra cache_map. You could try
the other compatible string in your .dts, but I doubt it'll help.

Hopefully the Realtek or Arm guys can shed some light.

Regards,
Andreas

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