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Message-Id: <c25cd134-9c53-5523-c4ad-faeef02e2af2@linux.vnet.ibm.com>
Date: Thu, 6 Apr 2017 12:13:23 +0530
From: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
To: Daniel Axtens <dja@...ens.net>, mpe@...erman.id.au
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
ego@...ux.vnet.ibm.com, bsingharora@...il.com,
benh@...nel.crashing.org, paulus@...ba.org, anton@...ba.org,
sukadev@...ux.vnet.ibm.com, mikey@...ling.org,
stewart@...ux.vnet.ibm.com, eranian@...gle.com,
Hemant Kumar <hemant@...ux.vnet.ibm.com>,
Anju T Sudhakar <anju@...ux.vnet.ibm.com>
Subject: Re: [PATCH v6 04/11] powerpc/perf: Add event attribute and group to
IMC pmus
On Tuesday 04 April 2017 07:41 AM, Daniel Axtens wrote:
> Hi,
>
>> Device tree IMC driver code parses the IMC units and their events. It
>> passes the information to IMC pmu code which is placed in powerpc/perf
>> as "imc-pmu.c".
>>
>> This patch creates only event attributes and attribute groups for the
>> IMC pmus.
>>
>> Signed-off-by: Anju T Sudhakar <anju@...ux.vnet.ibm.com>
>> Signed-off-by: Hemant Kumar <hemant@...ux.vnet.ibm.com>
>> Signed-off-by: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
>> ---
>> arch/powerpc/perf/Makefile | 6 +-
>> arch/powerpc/perf/imc-pmu.c | 97 +++++++++++++++++++++++++++++++
>> arch/powerpc/platforms/powernv/opal-imc.c | 12 +++-
>> 3 files changed, 112 insertions(+), 3 deletions(-)
>> create mode 100644 arch/powerpc/perf/imc-pmu.c
>>
>> diff --git a/arch/powerpc/perf/Makefile b/arch/powerpc/perf/Makefile
>> index 4d606b99a5cb..d0d1f04203c7 100644
>> --- a/arch/powerpc/perf/Makefile
>> +++ b/arch/powerpc/perf/Makefile
>> @@ -2,10 +2,14 @@ subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
>>
>> obj-$(CONFIG_PERF_EVENTS) += callchain.o perf_regs.o
>>
>> +imc-$(CONFIG_PPC_POWERNV) += imc-pmu.o
>> +
>> obj-$(CONFIG_PPC_PERF_CTRS) += core-book3s.o bhrb.o
>> obj64-$(CONFIG_PPC_PERF_CTRS) += power4-pmu.o ppc970-pmu.o power5-pmu.o \
>> power5+-pmu.o power6-pmu.o power7-pmu.o \
>> - isa207-common.o power8-pmu.o power9-pmu.o
>> + isa207-common.o power8-pmu.o power9-pmu.o \
>> + $(imc-y)
> Hmm, this seems... obtuse. Will the IMC stuff fail to compile on
> non-powerNV? Can we just link it in like we do with every other sort of
> performance counter and let runtime detection do its thing?
Yes. This is true. Also, in powernv_defconfig, we could
have perf_events config disabled. So will address this.
>
>> +
>> obj32-$(CONFIG_PPC_PERF_CTRS) += mpc7450-pmu.o
>>
>> obj-$(CONFIG_FSL_EMB_PERF_EVENT) += core-fsl-emb.o
>> diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
>> new file mode 100644
>> index 000000000000..ec464c76b749
>> --- /dev/null
>> +++ b/arch/powerpc/perf/imc-pmu.c
>> @@ -0,0 +1,97 @@
>> +/*
>> + * Nest Performance Monitor counter support.
>> + *
>> + * Copyright (C) 2016 Madhavan Srinivasan, IBM Corporation.
>> + * (C) 2016 Hemant K Shaw, IBM Corporation.
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License version 2 as published
>> + * by the Free Software Foundation.
>> + */
>> +#include <linux/perf_event.h>
>> +#include <linux/slab.h>
>> +#include <asm/opal.h>
>> +#include <asm/imc-pmu.h>
>> +#include <asm/cputhreads.h>
>> +#include <asm/smp.h>
>> +#include <linux/string.h>
>> +
>> +struct perchip_nest_info nest_perchip_info[IMC_MAX_CHIPS];
>> +struct imc_pmu *per_nest_pmu_arr[IMC_MAX_PMUS];
>> +
>> +/* dev_str_attr : Populate event "name" and string "str" in attribute */
>> +static struct attribute *dev_str_attr(const char *name, const char *str)
>> +{
>> + struct perf_pmu_events_attr *attr;
>> +
>> + attr = kzalloc(sizeof(*attr), GFP_KERNEL);
>> +
>> + sysfs_attr_init(&attr->attr.attr);
>> +
>> + attr->event_str = str;
>> + attr->attr.attr.name = name;
>> + attr->attr.attr.mode = 0444;
>> + attr->attr.show = perf_event_sysfs_show;
>> +
>> + return &attr->attr.attr;
>> +}
>> +
>> +/*
>> + * update_events_in_group: Update the "events" information in an attr_group
>> + * and assign the attr_group to the pmu "pmu".
>> + */
>> +static int update_events_in_group(struct imc_events *events,
>> + int idx, struct imc_pmu *pmu)
> So I've probably missed a key point in the earlier patches, but for the
> life of me I cannot figure out what idx is supposed to represent.
Ok will add comment. Idea is to keep track of number of events
to update when we create the event_attribute.
>
>> +{
>> + struct attribute_group *attr_group;
>> + struct attribute **attrs;
>> + int i;
>> +
>> + /* Allocate memory for attribute group */
>> + attr_group = kzalloc(sizeof(*attr_group), GFP_KERNEL);
>> + if (!attr_group)
>> + return -ENOMEM;
>> +
>> + /* Allocate memory for attributes */
>> + attrs = kzalloc((sizeof(struct attribute *) * (idx + 1)), GFP_KERNEL);
> Also, idx is an int, so:
> - things will go wrong if idx is -1
> - things will go very wrong if idx is -2
> - do you need to do some sort of validation to make sure it's within
> bounds? If not in this function, what function ensures the necessary
> 'sanity check' preconditions for idx?
Yes, valid point. Should add sanity check for this variable.
>
>> + if (!attrs) {
>> + kfree(attr_group);
>> + return -ENOMEM;
>> + }
>> +
>> + attr_group->name = "events";
>> + attr_group->attrs = attrs;
>> + for (i = 0; i < idx; i++, events++) {
>> + attrs[i] = dev_str_attr((char *)events->ev_name,
>> + (char *)events->ev_value);
>> + }
>> +
>> + pmu->attr_groups[0] = attr_group;
> Again, I may have missed something, but what's special about group 0?
> Patch 1 lets you have up to 4 groups - are they used elsewhere?
Each entry in the group is a specific attribute for the PMU unit.
So we use group 0 as event and group 1/2 as format and cpumask
attributes.
Will add comment to explain that.
>
>> + return 0;
>> +}
>> +
>> +/*
>> + * init_imc_pmu : Setup the IMC pmu device in "pmu_ptr" and its events
>> + * "events".
>> + * Setup the cpu mask information for these pmus and setup the state machine
>> + * hotplug notifiers as well.
> I cannot figure out how this function sets cpu mask information or sets
> up hotplug notifiers. Is this done in a later patch? (looking at the
> subject lines - perhaps patch 6?)
Yes. Its done in patch6, Will remove that text since it confusing here.
>
>> + */
>> +int init_imc_pmu(struct imc_events *events, int idx,
>> + struct imc_pmu *pmu_ptr)
> Should this be marked __init, or can it be called in a hotplug path?
Yes. I will.
>
>> +{
>> + int ret = -ENODEV;
>> +
>> + ret = update_events_in_group(events, idx, pmu_ptr);
>> + if (ret)
>> + goto err_free;
>> +
>> + return 0;
>> +
>> +err_free:
>> + /* Only free the attr_groups which are dynamically allocated */
>> + if (pmu_ptr->attr_groups[0]) {
>> + kfree(pmu_ptr->attr_groups[0]->attrs);
>> + kfree(pmu_ptr->attr_groups[0]);
>> + }
>> +
>> + return ret;
>> +}
>> diff --git a/arch/powerpc/platforms/powernv/opal-imc.c b/arch/powerpc/platforms/powernv/opal-imc.c
>> index ba0203e669c0..73c46703c2af 100644
>> --- a/arch/powerpc/platforms/powernv/opal-imc.c
>> +++ b/arch/powerpc/platforms/powernv/opal-imc.c
>> @@ -32,8 +32,11 @@
>> #include <asm/cputable.h>
>> #include <asm/imc-pmu.h>
>>
>> -struct perchip_nest_info nest_perchip_info[IMC_MAX_CHIPS];
>> -struct imc_pmu *per_nest_pmu_arr[IMC_MAX_PMUS];
>> +extern struct perchip_nest_info nest_perchip_info[IMC_MAX_CHIPS];
>> +extern struct imc_pmu *per_nest_pmu_arr[IMC_MAX_PMUS];
> Why are these definitions being moved?
> If they're still needed in this file, should the extern lines live in a
> header file?
We primarily use these values in the pmu functions. But will add
the extern to the header file.
Thanks for review
Maddy
>
>> +
>> +extern int init_imc_pmu(struct imc_events *events,
>> + int idx, struct imc_pmu *pmu_ptr);
>>
>> static int imc_event_info(char *name, struct imc_events *events)
>> {
>> @@ -379,6 +382,11 @@ static int imc_pmu_create(struct device_node *parent, int pmu_index)
>> idx += ret;
>> }
>>
>> + ret = init_imc_pmu(events, idx, pmu_ptr);
>> + if (ret) {
>> + pr_err("IMC PMU %s Register failed\n", pmu_ptr->pmu.name);
>> + goto free_events;
>> + }
>> return 0;
>>
>> free_events:
>> --
>> 2.7.4
> Regards,
> Daniel
>
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