* Yan, Zheng <zheng.z....@intel.com> wrote:
> On 04/18/2014 06:53 PM, Ingo Molnar wrote:
> >
> > * Yan, Zheng <zheng.z....@intel.com> wrote:
> >
> >> This patch adds support for building Intel uncore driver as module.
> >> It adds clean-up code and config option for the Intel uncore driver
> >>
> >> Signed-off-by: Yan, Zheng <zheng.z....@intel.com>
> >> ---
> >> Changes since v1:
> >> move config option to "General setup/Kernel Performance Events and
> >> Counters"
> >>
> >> arch/x86/kernel/cpu/Makefile | 3 +-
> >> arch/x86/kernel/cpu/perf_event_intel_uncore.c | 48
> >> ++++++++++++++++++++++++---
> >> init/Kconfig | 10 ++++++
> >> 3 files changed, 56 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
> >> index 7fd54f0..5d3da70 100644
> >> --- a/arch/x86/kernel/cpu/Makefile
> >> +++ b/arch/x86/kernel/cpu/Makefile
> >> @@ -36,7 +36,8 @@ obj-$(CONFIG_CPU_SUP_AMD) +=
> >> perf_event_amd_iommu.o
> >> endif
> >> obj-$(CONFIG_CPU_SUP_INTEL) += perf_event_p6.o
> >> perf_event_knc.o perf_event_p4.o
> >> obj-$(CONFIG_CPU_SUP_INTEL) += perf_event_intel_lbr.o
> >> perf_event_intel_ds.o perf_event_intel.o
> >> -obj-$(CONFIG_CPU_SUP_INTEL) += perf_event_intel_uncore.o
> >> perf_event_intel_rapl.o
> >> +obj-$(CONFIG_CPU_SUP_INTEL) += perf_event_intel_rapl.o
> >> +obj-$(CONFIG_PERF_X86_INTEL_UNCORE) += perf_event_intel_uncore.o
> >> endif
> >>
> >>
> >> diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c
> >> b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
> >> index 618d502..fd5e883 100644
> >> --- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c
> >> +++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
> >
> > So I'm not willing to apply this patch until the documentation of
> > perf_event_intel_uncore.c is improved. Right now the file starts
> > without a single comment (!). Just lines after lines of code, without
> > any explanation what it does, what its scope is, etc.
>
> there are comments mark the scope of code for different CPU.
>
> >
> > How should even a knowledgable user know about what it's all about?
> >
> > That problem percolates to the Kconfig entry as well:
> >
>
> Most of the codes without comments are hardware specific codes. The
> corresponding contents in Intel uncore documents are big
> tables/lists, nothing tricky/interesting. I really don't know how to
> comment these code.
Have a look at other PMU drivers, such as
arch/x86/kernel/cpu/perf_event_intel_rapl.c, which begin with a
general explanation attached below.
Thanks,
Ingo
/*
* perf_event_intel_rapl.c: support Intel RAPL energy consumption counters
* Copyright (C) 2013 Google, Inc., Stephane Eranian
*
* Intel RAPL interface is specified in the IA-32 Manual Vol3b
* section 14.7.1 (September 2013)
*
* RAPL provides more controls than just reporting energy consumption
* however here we only expose the 3 energy consumption free running
* counters (pp0, pkg, dram).
*
* Each of those counters increments in a power unit defined by the
* RAPL_POWER_UNIT MSR. On SandyBridge, this unit is 1/(2^16) Joules
* but it can vary.
*
* Counter to rapl events mappings:
*
* pp0 counter: consumption of all physical cores (power plane 0)
* event: rapl_energy_cores
* perf code: 0x1
*
* pkg counter: consumption of the whole processor package
* event: rapl_energy_pkg
* perf code: 0x2
*
* dram counter: consumption of the dram domain (servers only)
* event: rapl_energy_dram
* perf code: 0x3
*
* dram counter: consumption of the builtin-gpu domain (client only)
* event: rapl_energy_gpu
* perf code: 0x4
*
* We manage those counters as free running (read-only). They may be
* use simultaneously by other tools, such as turbostat.
*
* The events only support system-wide mode counting. There is no
* sampling support because it does not make sense and is not
* supported by the RAPL hardware.
*
* Because we want to avoid floating-point operations in the kernel,
* the events are all reported in fixed point arithmetic (32.32).
* Tools must adjust the counts to convert them to Watts using
* the duration of the measurement. Tools may use a function such as
* ldexp(raw_count, -32);
*/
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