Re: [PATCH v2 0/3] Arm CMN-600 PMU driver

From: Will Deacon <will@kernel.org>
To: "Zidenberg, Tsahi" <tsahee@amazon.com>
Cc: Robin Murphy <robin.murphy@arm.com>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"Saidi, Ali" <alisaidi@amazon.com>,
	"harb@amperecomputing.com" <harb@amperecomputing.com>,
	"tuanphan@os.amperecomputing.com"
	<tuanphan@os.amperecomputing.com>,
	"james.yang@arm.com" <james.yang@arm.com>,
	"patrik.berglund@arm.com" <patrik.berglund@arm.com>
Subject: Re: [PATCH v2 0/3] Arm CMN-600 PMU driver
Date: Mon, 5 Oct 2020 11:21:15 +0100	[thread overview]
Message-ID: <20201005102115.GA23702@willie-the-truck> (raw)
In-Reply-To: <55205AE5-EBBD-47F3-AA22-3B2A370CCF22@amazon.com>

On Mon, Oct 05, 2020 at 09:16:13AM +0000, Zidenberg, Tsahi wrote:
> 
> 
> On 18/09/2020, 16:29, "Robin Murphy" <robin.murphy@arm.com> wrote:
>     > Here's an update with some very minor cleanup tweaks, plus a proposal
>     > for some more in-depth debug information. Given that nobody seems to
>     > have any significant complaints about the interface, I assume we're all
>     > happy to merge the basic driver as-is and fix anything later if needed.
>     >
>     > Robin.
> 
> Agree with merging the driver as-is.
> Tested both the updated driver and the debugfs on Graviton2 (ACPI). 
> Both map and initial numbers seem right.
> 
> Tested-by: Tsahi Zidenberg <tsahee@amazon.com>
> 
> May I offer a small addition to the documentation?
> Something along these lines:
> 
> --- a/Documentation/admin-guide/perf/arm-cmn.rst
> +++ b/Documentation/admin-guide/perf/arm-cmn.rst
> @@ -41,8 +41,14 @@ specified by "occupid".
>  
>  By default each event provides an aggregate count over all nodes of the
>  given type. To target a specific node, "bynodeid" must be set to 1 and
> -"nodeid" to the appropriate value derived from the CMN configuration
> -(as defined in the "Node ID Mapping" section of the TRM).
> +"nodeid" to the appropriate value derived from the CMN configuration.
> +
> +The CMN map is available in /sys/kernel/debug/arm-cmn/map.
> +A nodeid could be calculated with this formulae:
> +  node-id = d | (p << 2) | (y << 3) | (x << (3 + xybits))
> +where:
> +  x,y,p,d are node location as can be seen in the map
> +  xybits is 2 for meshes <= 2*2, and 3 otherwise.

I already queued the driver, but if you send this as a stand-alone patch (on
top of the arm64 for-next/perf branch) then I'm happy to take it.

Thanks,

Will

>  Watchpoints
>  -----------
> 