[PATCH 22/37] drm/amdkfd: Add perf counters to topology

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On Sat, Dec 9, 2017 at 6:09 AM, Felix Kuehling <Felix.Kuehling at amd.com> wrote:
> From: Amber Lin <Amber.Lin at amd.com>
>
> For hardware blocks whose performance counters are accessed via MMIO
> registers, KFD provides the support for those privileged blocks. IOMMU is
> one of those privileged blocks. Most performance counter properties
> required by Thunk are available at /sys/bus/event_source/devices/amd_iommu.
>  This patch adds properties to topology in KFD sysfs for information not
> available in /sys/bus/event_source/devices/amd_iommu. They are shown at
> /sys/devices/virtual/kfd/kfd/topology/nodes/0/perf/iommu/ formatted as
> /sys/devices/virtual/kfd/kfd/topology/nodes/0/perf/<block>/<property>, i.e.
> /sys/devices/virtual/kfd/kfd/topology/nodes/0/perf/iommu/max_concurrent.
> For dGPUs, who don't have IOMMU, nothing appears under
> /sys/devices/virtual/kfd/kfd/topology/nodes/0/perf.

I don't feel comfortable with this patch. It seems to me you didn't
have anywhere to put these counters so you just stuck them in a place
the thunk already reads because it was "convenient" for you to do it.
But, as you point out in a comment later, these counters have nothing
to do with topology.
So this just feels wrong and I would like to:

a. get additional opinions on it. Christian ? Alex ? What do you think
? How the GPU's GFX counters are exposed ?
b. Ask why not use IOCTL to get the counters ?

btw, I tried to search for other drivers that do this (expose perf
counters in sysfs) and didn't find any (it wasn't an exhaustive search
so I may have missed).

Thanks,
Oded




>
> Signed-off-by: Amber Lin <Amber.Lin at amd.com>
> Signed-off-by: Kent Russell <kent.russell at amd.com>
> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
> ---
>  drivers/gpu/drm/amd/amdkfd/kfd_topology.c | 116 +++++++++++++++++++++++++++++-
>  drivers/gpu/drm/amd/amdkfd/kfd_topology.h |  13 ++++
>  2 files changed, 127 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
> index 7fe7ee0..52d20f5 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
> @@ -104,6 +104,7 @@ static void kfd_release_topology_device(struct kfd_topology_device *dev)
>         struct kfd_mem_properties *mem;
>         struct kfd_cache_properties *cache;
>         struct kfd_iolink_properties *iolink;
> +       struct kfd_perf_properties *perf;
>
>         list_del(&dev->list);
>
> @@ -128,6 +129,13 @@ static void kfd_release_topology_device(struct kfd_topology_device *dev)
>                 kfree(iolink);
>         }
>
> +       while (dev->perf_props.next != &dev->perf_props) {
> +               perf = container_of(dev->perf_props.next,
> +                               struct kfd_perf_properties, list);
> +               list_del(&perf->list);
> +               kfree(perf);
> +       }
> +
>         kfree(dev);
>  }
>
> @@ -162,6 +170,7 @@ struct kfd_topology_device *kfd_create_topology_device(
>         INIT_LIST_HEAD(&dev->mem_props);
>         INIT_LIST_HEAD(&dev->cache_props);
>         INIT_LIST_HEAD(&dev->io_link_props);
> +       INIT_LIST_HEAD(&dev->perf_props);
>
>         list_add_tail(&dev->list, device_list);
>
> @@ -328,6 +337,39 @@ static struct kobj_type cache_type = {
>         .sysfs_ops = &cache_ops,
>  };
>
> +/****** Sysfs of Performance Counters ******/
> +
> +struct kfd_perf_attr {
> +       struct kobj_attribute attr;
> +       uint32_t data;
> +};
> +
> +static ssize_t perf_show(struct kobject *kobj, struct kobj_attribute *attrs,
> +                       char *buf)
> +{
> +       struct kfd_perf_attr *attr;
> +
> +       buf[0] = 0;
> +       attr = container_of(attrs, struct kfd_perf_attr, attr);
> +       if (!attr->data) /* invalid data for PMC */
> +               return 0;
> +       else
> +               return sysfs_show_32bit_val(buf, attr->data);
> +}
> +
> +#define KFD_PERF_DESC(_name, _data)                    \
> +{                                                      \
> +       .attr  = __ATTR(_name, 0444, perf_show, NULL),  \
> +       .data = _data,                                  \
> +}
> +
> +static struct kfd_perf_attr perf_attr_iommu[] = {
> +       KFD_PERF_DESC(max_concurrent, 0),
> +       KFD_PERF_DESC(num_counters, 0),
> +       KFD_PERF_DESC(counter_ids, 0),
> +};
> +/****************************************/
> +
>  static ssize_t node_show(struct kobject *kobj, struct attribute *attr,
>                 char *buffer)
>  {
> @@ -452,6 +494,7 @@ static void kfd_remove_sysfs_node_entry(struct kfd_topology_device *dev)
>         struct kfd_iolink_properties *iolink;
>         struct kfd_cache_properties *cache;
>         struct kfd_mem_properties *mem;
> +       struct kfd_perf_properties *perf;
>
>         if (dev->kobj_iolink) {
>                 list_for_each_entry(iolink, &dev->io_link_props, list)
> @@ -488,6 +531,16 @@ static void kfd_remove_sysfs_node_entry(struct kfd_topology_device *dev)
>                 dev->kobj_mem = NULL;
>         }
>
> +       if (dev->kobj_perf) {
> +               list_for_each_entry(perf, &dev->perf_props, list) {
> +                       kfree(perf->attr_group);
> +                       perf->attr_group = NULL;
> +               }
> +               kobject_del(dev->kobj_perf);
> +               kobject_put(dev->kobj_perf);
> +               dev->kobj_perf = NULL;
> +       }
> +
>         if (dev->kobj_node) {
>                 sysfs_remove_file(dev->kobj_node, &dev->attr_gpuid);
>                 sysfs_remove_file(dev->kobj_node, &dev->attr_name);
> @@ -504,8 +557,10 @@ static int kfd_build_sysfs_node_entry(struct kfd_topology_device *dev,
>         struct kfd_iolink_properties *iolink;
>         struct kfd_cache_properties *cache;
>         struct kfd_mem_properties *mem;
> +       struct kfd_perf_properties *perf;
>         int ret;
> -       uint32_t i;
> +       uint32_t i, num_attrs;
> +       struct attribute **attrs;
>
>         if (WARN_ON(dev->kobj_node))
>                 return -EEXIST;
> @@ -534,6 +589,10 @@ static int kfd_build_sysfs_node_entry(struct kfd_topology_device *dev,
>         if (!dev->kobj_iolink)
>                 return -ENOMEM;
>
> +       dev->kobj_perf = kobject_create_and_add("perf", dev->kobj_node);
> +       if (!dev->kobj_perf)
> +               return -ENOMEM;
> +
>         /*
>          * Creating sysfs files for node properties
>          */
> @@ -611,7 +670,33 @@ static int kfd_build_sysfs_node_entry(struct kfd_topology_device *dev,
>                 if (ret < 0)
>                         return ret;
>                 i++;
> -}
> +       }
> +
> +       /* All hardware blocks have the same number of attributes. */
> +       num_attrs = sizeof(perf_attr_iommu)/sizeof(struct kfd_perf_attr);
> +       list_for_each_entry(perf, &dev->perf_props, list) {
> +               perf->attr_group = kzalloc(sizeof(struct kfd_perf_attr)
> +                       * num_attrs + sizeof(struct attribute_group),
> +                       GFP_KERNEL);
> +               if (!perf->attr_group)
> +                       return -ENOMEM;
> +
> +               attrs = (struct attribute **)(perf->attr_group + 1);
> +               if (!strcmp(perf->block_name, "iommu")) {
> +               /* Information of IOMMU's num_counters and counter_ids is shown
> +                * under /sys/bus/event_source/devices/amd_iommu. We don't
> +                * duplicate here.
> +                */
> +                       perf_attr_iommu[0].data = perf->max_concurrent;
> +                       for (i = 0; i < num_attrs; i++)
> +                               attrs[i] = &perf_attr_iommu[i].attr.attr;
> +               }
> +               perf->attr_group->name = perf->block_name;
> +               perf->attr_group->attrs = attrs;
> +               ret = sysfs_create_group(dev->kobj_perf, perf->attr_group);
> +               if (ret < 0)
> +                       return ret;
> +       }
>
>         return 0;
>  }
> @@ -778,6 +863,29 @@ static void find_system_memory(const struct dmi_header *dm,
>                 }
>         }
>  }
> +
> +/*
> + * Performance counters information is not part of CRAT but we would like to
> + * put them in the sysfs under topology directory for Thunk to get the data.
> + * This function is called before updating the sysfs.
> + */
> +static int kfd_add_perf_to_topology(struct kfd_topology_device *kdev)
> +{
> +       struct kfd_perf_properties *props;
> +
> +       if (amd_iommu_pc_supported()) {
> +               props = kfd_alloc_struct(props);
> +               if (!props)
> +                       return -ENOMEM;
> +               strcpy(props->block_name, "iommu");
> +               props->max_concurrent = amd_iommu_pc_get_max_banks(0) *
> +                       amd_iommu_pc_get_max_counters(0); /* assume one iommu */
> +               list_add_tail(&props->list, &kdev->perf_props);
> +       }
> +
> +       return 0;
> +}
> +
>  /* kfd_add_non_crat_information - Add information that is not currently
>   *     defined in CRAT but is necessary for KFD topology
>   * @dev - topology device to which addition info is added
> @@ -860,6 +968,10 @@ int kfd_topology_init(void)
>                 }
>         }
>
> +       kdev = list_first_entry(&temp_topology_device_list,
> +                               struct kfd_topology_device, list);
> +       kfd_add_perf_to_topology(kdev);
> +
>         down_write(&topology_lock);
>         kfd_topology_update_device_list(&temp_topology_device_list,
>                                         &topology_device_list);
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_topology.h b/drivers/gpu/drm/amd/amdkfd/kfd_topology.h
> index 55de56f..b9f3142 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_topology.h
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_topology.h
> @@ -134,6 +134,13 @@ struct kfd_iolink_properties {
>         struct attribute        attr;
>  };
>
> +struct kfd_perf_properties {
> +       struct list_head        list;
> +       char                    block_name[16];
> +       uint32_t                max_concurrent;
> +       struct attribute_group  *attr_group;
> +};
> +
>  struct kfd_topology_device {
>         struct list_head                list;
>         uint32_t                        gpu_id;
> @@ -144,11 +151,13 @@ struct kfd_topology_device {
>         struct list_head                cache_props;
>         uint32_t                        io_link_count;
>         struct list_head                io_link_props;
> +       struct list_head                perf_props;
>         struct kfd_dev                  *gpu;
>         struct kobject                  *kobj_node;
>         struct kobject                  *kobj_mem;
>         struct kobject                  *kobj_cache;
>         struct kobject                  *kobj_iolink;
> +       struct kobject                  *kobj_perf;
>         struct attribute                attr_gpuid;
>         struct attribute                attr_name;
>         struct attribute                attr_props;
> @@ -173,4 +182,8 @@ struct kfd_topology_device *kfd_create_topology_device(
>                 struct list_head *device_list);
>  void kfd_release_topology_device_list(struct list_head *device_list);
>
> +extern bool amd_iommu_pc_supported(void);
> +extern u8 amd_iommu_pc_get_max_banks(u16 devid);
> +extern u8 amd_iommu_pc_get_max_counters(u16 devid);
> +
>  #endif /* __KFD_TOPOLOGY_H__ */
> --
> 2.7.4
>


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