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Date: Fri, 9 Sep 2016 23:21:19 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: "Pan, Harry" <harry.pan@...el.com>
cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"peterz@...radead.org" <peterz@...radead.org>,
"ray.huang@....com" <ray.huang@....com>,
"x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
"srinivas.pandruvada@...ux.intel.com"
<srinivas.pandruvada@...ux.intel.com>,
"mingo@...hat.com" <mingo@...hat.com>,
"bp@...en8.de" <bp@...en8.de>
Subject: Re: [PATCH 2/2] perf/x86/rapl: Enable Baytrail/Braswell RAPL
support
On Fri, 9 Sep 2016, Pan, Harry wrote:
> On Fri, 2016-09-09 at 17:11 +0200, Thomas Gleixner wrote:
> > > struct intel_rapl_init_fun {
> > > - bool apply_quirk;
> > > + enum rapl_quirk apply_quirk;
> >
> > This is silly. Make apply_quirk a function pointer and provide functions
> > for the different quirks.
> I read the rapl_check_hw_unit() as: read MSR_RAPL_POWER_UNIT, apply
> quirk if need, then estimate timer rate.
>
> In case to refine struct intel_rapl_init_fun adding callback, then
> either the quirk moving outside the rapl_check_hw_unit(), or replace
> input parameter as whole rapl_init in order to assess quirk callback, by
> far it looks to me centralize these two quirks inside this function more
> easily to maintain.
If you have more than 3 quirks then the function becomes completely
unreadable while with a function pointer nobody has to touch it when adding
a new quirk. Neither do you have to update enums.
> > Zero ininitalization has no real value other than consuming state space.
> To enable more than one quirk I extended bool to enum, I thought the
> __initconst space would be freed after kernel initialized, is there more
> detail concern I missed?
I meant screen space. What's the point of zero initialization other than
consuming code lines and providing zero information?
But instead of arguing with you in circles I took the 5 minutes to make it
function pointer based. Patch below.
Thanks,
tglx
8<-------------------
Subject: x86/perf/rapl: Make quirk a function pointer
From: Thomas Gleixner <tglx@...utronix.de>
Date: Fri, 09 Sep 2016 22:46:17 +0200
There are more model specific quirks required. So we need to change the
single purpose boolean quirk flag to an easy extensible mechanism.
Make the quirk a function pointer and move the existing quirk into its own
function.
While at it make the init struct initializers readable and rename the
misnomed intel_rapl_hw_init_fun struct to intel_rapl_model_desc because
that's what it is a cpu model descriptor for the rapl features specific to
a particular model.
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
arch/x86/events/intel/rapl.c | 92 +++++++++++++++++++++----------------------
1 file changed, 46 insertions(+), 46 deletions(-)
--- a/arch/x86/events/intel/rapl.c
+++ b/arch/x86/events/intel/rapl.c
@@ -152,6 +152,12 @@ struct rapl_pmus {
struct rapl_pmu *pmus[];
};
+struct intel_rapl_model_desc {
+ void (*quirk)(void);;
+ int cntr_mask;
+ struct attribute **attrs;
+};
+
/* 1/2^hw_unit Joule */
static int rapl_hw_unit[NR_RAPL_DOMAINS] __read_mostly;
static struct rapl_pmus *rapl_pmus;
@@ -617,7 +623,18 @@ static int rapl_cpu_prepare(unsigned int
return 0;
}
-static int rapl_check_hw_unit(bool apply_quirk)
+static void rapl_hsx_quirk(void)
+{
+ /*
+ * DRAM domain on HSW server and KNL has fixed energy unit which can be
+ * different than the unit from power unit MSR. See
+ * "Intel Xeon Processor E5-1600 and E5-2600 v3 Product Families, V2
+ * of 2. Datasheet, September 2014, Reference Number: 330784-001 "
+ */
+ rapl_hw_unit[RAPL_IDX_RAM_NRG_STAT] = 16;
+}
+
+static int rapl_check_hw_unit(const struct intel_rapl_model_desc *model)
{
u64 msr_rapl_power_unit_bits;
int i;
@@ -628,14 +645,9 @@ static int rapl_check_hw_unit(bool apply
for (i = 0; i < NR_RAPL_DOMAINS; i++)
rapl_hw_unit[i] = (msr_rapl_power_unit_bits >> 8) & 0x1FULL;
- /*
- * DRAM domain on HSW server and KNL has fixed energy unit which can be
- * different than the unit from power unit MSR. See
- * "Intel Xeon Processor E5-1600 and E5-2600 v3 Product Families, V2
- * of 2. Datasheet, September 2014, Reference Number: 330784-001 "
- */
- if (apply_quirk)
- rapl_hw_unit[RAPL_IDX_RAM_NRG_STAT] = 16;
+ /* Apply quirk before initializing the timer rate */
+ if (model->quirk)
+ model->quirk();
/*
* Calculate the timer rate:
@@ -701,46 +713,36 @@ static int __init init_rapl_pmus(void)
#define X86_RAPL_MODEL_MATCH(model, init) \
{ X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, (unsigned long)&init }
-struct intel_rapl_init_fun {
- bool apply_quirk;
- int cntr_mask;
- struct attribute **attrs;
-};
-
-static const struct intel_rapl_init_fun snb_rapl_init __initconst = {
- .apply_quirk = false,
- .cntr_mask = RAPL_IDX_CLN,
- .attrs = rapl_events_cln_attr,
+static const struct intel_rapl_model_desc snb_rapl_init __initconst = {
+ .cntr_mask = RAPL_IDX_CLN,
+ .attrs = rapl_events_cln_attr,
};
-static const struct intel_rapl_init_fun hsx_rapl_init __initconst = {
- .apply_quirk = true,
- .cntr_mask = RAPL_IDX_SRV,
- .attrs = rapl_events_srv_attr,
+static const struct intel_rapl_model_desc hsx_rapl_init __initconst = {
+ .quirk = rapl_hsx_quirk,
+ .cntr_mask = RAPL_IDX_SRV,
+ .attrs = rapl_events_srv_attr,
};
-static const struct intel_rapl_init_fun hsw_rapl_init __initconst = {
- .apply_quirk = false,
- .cntr_mask = RAPL_IDX_HSW,
- .attrs = rapl_events_hsw_attr,
+static const struct intel_rapl_model_desc hsw_rapl_init __initconst = {
+ .cntr_mask = RAPL_IDX_HSW,
+ .attrs = rapl_events_hsw_attr,
};
-static const struct intel_rapl_init_fun snbep_rapl_init __initconst = {
- .apply_quirk = false,
- .cntr_mask = RAPL_IDX_SRV,
- .attrs = rapl_events_srv_attr,
+static const struct intel_rapl_model_desc snbep_rapl_init __initconst = {
+ .cntr_mask = RAPL_IDX_SRV,
+ .attrs = rapl_events_srv_attr,
};
-static const struct intel_rapl_init_fun knl_rapl_init __initconst = {
- .apply_quirk = true,
- .cntr_mask = RAPL_IDX_KNL,
- .attrs = rapl_events_knl_attr,
+static const struct intel_rapl_model_desc knl_rapl_init __initconst = {
+ .quirk = rapl_hsx_quirk,
+ .cntr_mask = RAPL_IDX_KNL,
+ .attrs = rapl_events_knl_attr,
};
-static const struct intel_rapl_init_fun skl_rapl_init __initconst = {
- .apply_quirk = false,
- .cntr_mask = RAPL_IDX_SKL_CLN,
- .attrs = rapl_events_skl_attr,
+static const struct intel_rapl_model_desc skl_rapl_init __initconst = {
+ .cntr_mask = RAPL_IDX_SKL_CLN,
+ .attrs = rapl_events_skl_attr,
};
static const struct x86_cpu_id rapl_cpu_match[] __initconst = {
@@ -772,21 +774,19 @@ MODULE_DEVICE_TABLE(x86cpu, rapl_cpu_mat
static int __init rapl_pmu_init(void)
{
+ const struct intel_rapl_model_desc *model;
const struct x86_cpu_id *id;
- struct intel_rapl_init_fun *rapl_init;
- bool apply_quirk;
int ret;
id = x86_match_cpu(rapl_cpu_match);
if (!id)
return -ENODEV;
- rapl_init = (struct intel_rapl_init_fun *)id->driver_data;
- apply_quirk = rapl_init->apply_quirk;
- rapl_cntr_mask = rapl_init->cntr_mask;
- rapl_pmu_events_group.attrs = rapl_init->attrs;
+ model = (struct intel_rapl_model_desc*)id->driver_data;
+ rapl_cntr_mask = model->cntr_mask;
+ rapl_pmu_events_group.attrs = model->attrs;
- ret = rapl_check_hw_unit(apply_quirk);
+ ret = rapl_check_hw_unit(model);
if (ret)
return ret;
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