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Message-ID: <20151023132702.GC2844@pd.tnic>
Date: Fri, 23 Oct 2015 15:27:02 +0200
From: Borislav Petkov <bp@...e.de>
To: Huang Rui <ray.huang@....com>
Cc: Guenter Roeck <linux@...ck-us.net>,
Peter Zijlstra <peterz@...radead.org>,
Jean Delvare <jdelvare@...e.de>,
Andy Lutomirski <luto@...capital.net>,
Andreas Herrmann <herrmann.der.user@...il.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...nel.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Len Brown <lenb@...nel.org>,
John Stultz <john.stultz@...aro.org>,
Frédéric Weisbecker <fweisbec@...il.com>,
lm-sensors@...sensors.org, linux-kernel@...r.kernel.org,
x86@...nel.org,
Andreas Herrmann <herrmann.der.user@...glemail.com>,
Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>,
Fengguang Wu <fengguang.wu@...el.com>,
Aaron Lu <aaron.lu@...el.com>, Tony Li <tony.li@....com>
Subject: Re: [PATCH v2 05/10] hwmon: (fam15h_power) Add compute unit
accumulated power
On Tue, Oct 20, 2015 at 10:28:24AM +0800, Huang Rui wrote:
> This patch adds a member in fam15h_power_data which specifies the
> compute unit accumulated power. It adds do_read_registers_on_cu to do
> all the read to all MSRs and run it on one of the online cores on each
> compute unit with smp_call_function_many(). This behavior can decrease
> IPI numbers.
>
> Suggested-by: Borislav Petkov <bp@...en8.de>
> Signed-off-by: Huang Rui <ray.huang@....com>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Ingo Molnar <mingo@...nel.org>
> ---
> drivers/hwmon/fam15h_power.c | 68 +++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 67 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwmon/fam15h_power.c b/drivers/hwmon/fam15h_power.c
> index e2bfab5..88e4f3e 100644
> --- a/drivers/hwmon/fam15h_power.c
> +++ b/drivers/hwmon/fam15h_power.c
> @@ -25,6 +25,7 @@
> #include <linux/module.h>
> #include <linux/pci.h>
> #include <linux/bitops.h>
> +#include <linux/cpumask.h>
> #include <asm/processor.h>
> #include <asm/msr.h>
>
> @@ -44,7 +45,9 @@ MODULE_LICENSE("GPL");
>
> #define FAM15H_MIN_NUM_ATTRS 2
> #define FAM15H_NUM_GROUPS 2
> +#define MAX_CUS 8
>
> +#define MSR_F15H_CU_PWR_ACCUMULATOR 0xc001007a
> #define MSR_F15H_CU_MAX_PWR_ACCUMULATOR 0xc001007b
>
> struct fam15h_power_data {
> @@ -57,6 +60,8 @@ struct fam15h_power_data {
> struct attribute_group fam15h_power_group;
> /* maximum accumulated power of a compute unit */
> u64 max_cu_acc_power;
> + /* accumulated power of the compute units */
> + u64 cu_acc_power[MAX_CUS];
> };
>
> static ssize_t show_power(struct device *dev,
> @@ -115,6 +120,65 @@ static ssize_t show_power_crit(struct device *dev,
> }
> static DEVICE_ATTR(power1_crit, S_IRUGO, show_power_crit, NULL);
>
> +static void do_read_registers_on_cu(void *_data)
> +{
> + struct fam15h_power_data *data = _data;
> + int cpu, cu, cores_per_cu;
> +
> + cpu = smp_processor_id();
> +
> + cores_per_cu = amd_get_cores_per_cu();
> + cu = cpu / cores_per_cu;
> +
> + WARN_ON(rdmsrl_safe(MSR_F15H_CU_PWR_ACCUMULATOR,
> + &data->cu_acc_power[cu]));
I guess the WARN_ON's here should be WARN_ON_ONCE() - otherwise dmesg is
filling up very quickly.
> +}
> +
> +static int read_registers(struct fam15h_power_data *data)
> +{
> + int this_cpu, ret;
> + int cu_num, cores_per_cu, cpu, cu;
> + cpumask_var_t mask;
> +
> + cores_per_cu = amd_get_cores_per_cu();
> + cu_num = boot_cpu_data.x86_max_cores / cores_per_cu;
> +
> + WARN_ON_ONCE(cu_num > MAX_CUS);
> +
> + ret = zalloc_cpumask_var(&mask, GFP_KERNEL);
> + if (!ret)
> + return -ENOMEM;
> +
> + this_cpu = get_cpu();
This should be get_online_cpus() and its counterpart below should be
put_online_cpus().
> +
> + /*
> + * Choose the first online core of each compute unit, and then
> + * read their MSR value of power and ptsc in one time of IPI,
in a single IPI.
> + * because the MSR value of cpu core represent the compute
s/cpu/CPU/
do that in *all* your text.
> + * unit's. This behavior can decrease IPI numbers between the
unit's ?
What does that sentence even mean?
> + * cores.
> + */
> + cpu = cpumask_first(cpu_online_mask);
> + cu = cpu / cores_per_cu;
> + while (cpu < boot_cpu_data.x86_max_cores) {
> + if (cu <= cpu / cores_per_cu) {
> + cu = cpu / cores_per_cu + 1;
> + cpumask_set_cpu(cpu, mask);
> + }
> + cpu = cpumask_next(cu * cores_per_cu - 1, cpu_online_mask);
> + }
This is hard to parse - I *think* you're setting a bit in mask for a
core in each CU...
If so, I think you can simplify it by generating a tmp mask which
contains the cores of CU0, i.e. something like that:
11_00_00_...
and then do cpumask_and(res, ...) to find the online cores on that CU
and then do cpumask_set_cpu(cpumask_any(res), mask) to select one CPU on
that CU.
And then shift to the next CU:
cpumask_shift_right(dst, src_mask, cores_per_cu);
I think this should be cleaner and less error prone, without the
conditionals...
> +
> + if (cpumask_test_cpu(this_cpu, mask))
> + do_read_registers_on_cu(data);
> +
> + smp_call_function_many(mask, do_read_registers_on_cu, data, true);
> + put_cpu();
> +
> + free_cpumask_var(mask);
> +
> + return 0;
> +}
> +
> static int fam15h_power_init_attrs(struct pci_dev *pdev,
> struct fam15h_power_data *data)
> {
> @@ -253,7 +317,9 @@ static int fam15h_power_init_data(struct pci_dev *f4,
>
> data->max_cu_acc_power = tmp;
>
> - return 0;
> + ret = read_registers(data);
> +
> + return ret;
Simply:
return read_registers(data);
> }
>
> static int fam15h_power_probe(struct pci_dev *pdev,
> --
> 1.9.1
>
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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