linux-kernel - Re: [PATCH 1/6] perf x86: Infrastructure for exposing an Uncore unit to PMON mapping

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Message-ID: <20191202140059.GL2844@hirez.programming.kicks-ass.net>
Date:   Mon, 2 Dec 2019 15:00:59 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     roman.sudarikov@...ux.intel.com
Cc:     mingo@...hat.com, acme@...nel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...hat.com,
        namhyung@...nel.org, linux-kernel@...r.kernel.org,
        eranian@...gle.com, bgregg@...flix.com, ak@...ux.intel.com,
        kan.liang@...ux.intel.com, alexander.antonov@...el.com
Subject: Re: [PATCH 1/6] perf x86: Infrastructure for exposing an Uncore unit
 to PMON mapping

On Tue, Nov 26, 2019 at 07:36:25PM +0300, roman.sudarikov@...ux.intel.com wrote:
> From: Roman Sudarikov <roman.sudarikov@...ux.intel.com>
> 
> Intel® Xeon® Scalable processor family (code name Skylake-SP) makes significant
> changes in the integrated I/O (IIO) architecture. The new solution introduces
> IIO stacks which are responsible for managing traffic between the PCIe domain
> and the Mesh domain. Each IIO stack has its own PMON block and can handle either
> DMI port, x16 PCIe root port, MCP-Link or various built-in accelerators.
> IIO PMON blocks allow concurrent monitoring of I/O flows up to 4 x4 bifurcation
> within each IIO stack.
> 
> Software is supposed to program required perf counters within each IIO stack
> and gather performance data. The tricky thing here is that IIO PMON reports data
> per IIO stack but users have no idea what IIO stacks are - they only know devices
> which are connected to the platform.
> 
> Understanding IIO stack concept to find which IIO stack that particular IO device
> is connected to, or to identify an IIO PMON block to program for monitoring
> specific IIO stack assumes a lot of implicit knowledge about given Intel server
> platform architecture.
> 
> This patch set introduces:
>     An infrastructure for exposing an Uncore unit to Uncore PMON mapping through sysfs-backend
>     A new --iiostat mode in perf stat to provide I/O performance metrics per I/O device
> 
> Current version supports a server line starting Intel® Xeon® Processor Scalable
> Family and introduces mapping for IIO Uncore units only.
> Other units can be added on demand.
> 
> Usage example:
>     /sys/devices/uncore_<type>_<pmu_idx>/platform_mapping
> 
> Each Uncore unit type, by its nature, can be mapped to its own context, for example:
>     CHA - each uncore_cha_<pmu_idx> is assigned to manage a distinct slice of LLC capacity
>     UPI - each uncore_upi_<pmu_idx> is assigned to manage one link of Intel UPI Subsystem
>     IIO - each uncore_iio_<pmu_idx> is assigned to manage one stack of the IIO module
>     IMC - each uncore_imc_<pmu_idx> is assigned to manage one channel of Memory Controller
> 
> Implementation details:
>     Two callbacks added to struct intel_uncore_type to discover and map Uncore units to PMONs:
>         int (*get_topology)(struct intel_uncore_type *type)
>         int (*set_mapping)(struct intel_uncore_type *type)
> 
>     IIO stack to PMON mapping is exposed through
>         /sys/devices/uncore_iio_<pmu_idx>/platform_mapping
>         in the following format: domain:bus
> 
> Details of IIO Uncore unit mapping to IIO PMON:
> Each IIO stack is either a DMI port, x16 PCIe root port, MCP-Link or various
> built-in accelerators. For Uncore IIO Unit type, the platform_mapping file
> holds bus numbers of devices, which can be monitored by that IIO PMON block
> on each die.
> 
> For example, on a 4-die Intel Xeon® server platform:
>     $ cat /sys/devices/uncore_iio_0/platform_mapping
>     0000:00,0000:40,0000:80,0000:c0
> 
> Which means:
> IIO PMON block 0 on die 0 belongs to IIO stack located on bus 0x00, domain 0x0000
> IIO PMON block 0 on die 1 belongs to IIO stack located on bus 0x40, domain 0x0000
> IIO PMON block 0 on die 2 belongs to IIO stack located on bus 0x80, domain 0x0000
> IIO PMON block 0 on die 3 belongs to IIO stack located on bus 0xc0, domain 0x0000
> 
> Signed-off-by: Roman Sudarikov <roman.sudarikov@...ux.intel.com>
> Co-developed-by: Alexander Antonov <alexander.antonov@...el.com>
> Signed-off-by: Alexander Antonov <alexander.antonov@...el.com>

Kan, can you help these people? There's a ton of process fail with this
submission. From SoB chain to CodingStyle to git-sendmail threading.