Re: [PATCH] drm/i915: expose energy counter on SNB and IVB

[Ben Widawsky <ben@bwidawsk.net>]

On Wed, 20 Jun 2012 14:48:58 -0700
Jesse Barnes <jbarnes@virtuousgeek.org> wrote:

> On SNB and IVB, there's an MSR (also exposed through MCHBAR) we can use
> to read out the amount of energy used over time.  Expose this in sysfs
> to make it easy to do power comparisons with different configurations.
> 
> If the platform supports it, the file will show up under the
> drm/card0/power subdirectory of the PCI device in sysfs as gt_energy_uJ.
> The value in the file is a running total of energy (in microjoules)
> consumed by the graphics device.
> 
> v2: move to sysfs (Ben, Daniel)
>     expose a simple value (Chris)
>     drop unrelated hunk (Ben)
> 
> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

I have some complaints, and a bikeshed - but it's
Acked-by: Ben Widawsky <ben@bwidawsk.net>
either way.

And color-me-danvet, but I kind of get why review is so mean on ABI
stuff.

I don't really care whether you address the other complaints, but I
won't do a a proper reviewed-by until the doc complaints are addressed.

> ---
>  drivers/gpu/drm/i915/i915_reg.h   |    2 +
>  drivers/gpu/drm/i915/i915_sysfs.c |   39 +++++++++++++++++++++++++++++++++++++
>  2 files changed, 41 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 0a61481..ca6a620 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1224,6 +1224,8 @@
>  #define CLKCFG_MEM_800					(3 << 4)
>  #define CLKCFG_MEM_MASK					(7 << 4)
>  
> +#define SECP_NRG_STTS			(MCHBAR_MIRROR_BASE_SNB + 0x592c)
> +

I can't find where this is defined, so it's hard to review. Could you
please point me to the docs for this?

>  #define TSC1			0x11001
>  #define   TSE			(1<<0)
>  #define TR1			0x11006
> diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
> index 2f5388a..c7fe7bd 100644
> --- a/drivers/gpu/drm/i915/i915_sysfs.c
> +++ b/drivers/gpu/drm/i915/i915_sysfs.c
> @@ -93,6 +93,37 @@ static struct attribute_group rc6_attr_group = {
>  	.attrs =  rc6_attrs
>  };
>  
> +#define MSR_IA32_PACKAGE_POWER_SKU_UNIT		0x00000606

I honestly didn't try to look for this definition, but let's assume I
can't find it. Where is this one?

> +
> +static ssize_t
> +show_gt_energy_uJ(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct drm_minor *dminor = container_of(dev, struct drm_minor, kdev);
> +	struct drm_i915_private *dev_priv = dminor->dev->dev_private;
> +	u64 ppsu;
> +	u32 val, units;
> +
> +	rdmsrl(MSR_IA32_PACKAGE_POWER_SKU_UNIT, ppsu);
> +
> +	ppsu = (ppsu & 0x1f00) >> 8;
> +	units = 1000000 / (1 << ppsu); /* convert to uJ */
> +	val = I915_READ(SECP_NRG_STTS);
> +
> +	return snprintf(buf, PAGE_SIZE, "%u", val * units);
> +}
> +
> +static DEVICE_ATTR(gt_energy_uJ, S_IRUGO, show_gt_energy_uJ, NULL);
> +
> +static struct attribute *gt_attrs[] = {
> +	&dev_attr_gt_energy_uJ.attr,
> +	NULL,
> +};

I think convention dictates it should be all lowercase. And while on
that, gt_energy_uJ is about as descriptive a name as rc6 (what jerk
named that anyway?). I think something like consumed_microjoules is
better.

> +
> +static struct attribute_group gt_attr_group = {
> +	.name = power_group_name,
> +	.attrs = gt_attrs,
> +};
> +
>  static int l3_access_valid(struct drm_device *dev, loff_t offset)
>  {
>  	if (!IS_IVYBRIDGE(dev))
> @@ -217,10 +248,18 @@ void i915_setup_sysfs(struct drm_device *dev)
>  		if (ret)
>  			DRM_ERROR("l3 parity sysfs setup failed\n");
>  	}
> +
> +	if (IS_GEN6(dev) || IS_IVYBRIDGE(dev)) {
> +		ret = sysfs_merge_group(&dev->primary->kdev.kobj,
> +					&gt_attr_group);
> +		if (ret)
> +			DRM_ERROR("GT energy sysfs setup failed\n");
> +	}
>  }
>  
>  void i915_teardown_sysfs(struct drm_device *dev)
>  {
>  	device_remove_bin_file(&dev->primary->kdev,  &dpf_attrs);
>  	sysfs_unmerge_group(&dev->primary->kdev.kobj, &rc6_attr_group);
> +	sysfs_unmerge_group(&dev->primary->kdev.kobj, &gt_attr_group);
>  }

teardown should occur in reverse of init, so I'd put this on top.



-- 
Ben Widawsky, Intel Open Source Technology Center