Re: [PATCH 7/9] drm/i915/perf: Allow dynamic reconfiguration of the OA stream

[Lionel Landwerlin <lionel.g.landwerlin@intel.com>]

On 10/10/2019 00:19, Chris Wilson wrote:
> From: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
>
> Introduce a new perf_ioctl command to change the OA configuration of the
> active stream. This allows the OA stream to be reconfigured between
> batch buffers, giving greater flexibility in sampling. We inject a
> request into the OA context to reconfigure the stream asynchronously on
> the GPU in between and ordered with execbuffer calls.
>
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>


So much simpler :)


> ---
>   drivers/gpu/drm/i915/i915_perf.c | 34 +++++++++++++++++++++++++++++++-
>   include/uapi/drm/i915_drm.h      | 10 ++++++++++
>   2 files changed, 43 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
> index 12cc47aece21..3b77db8995f3 100644
> --- a/drivers/gpu/drm/i915/i915_perf.c
> +++ b/drivers/gpu/drm/i915/i915_perf.c
> @@ -2856,6 +2856,28 @@ static void i915_perf_disable_locked(struct i915_perf_stream *stream)
>   		stream->ops->disable(stream);
>   }
>   
> +static int i915_perf_config_locked(struct i915_perf_stream *stream,
> +				   unsigned long metrics_set)
> +{
> +	struct i915_oa_config *config;
> +	int err = 0;
> +
> +	config = i915_perf_get_oa_config(stream->perf, metrics_set);
> +	if (!config)
> +		return -EINVAL;
> +
> +	if (config != stream->oa_config) {
> +		if (stream->pinned_ctx)
> +			err = emit_oa_config(stream, stream->pinned_ctx);
> +		if (err == 0)
> +			config = xchg(&stream->oa_config, config);
> +	}
> +
> +	i915_oa_config_put(config);
> +
> +	return err;
> +}
> +
>   /**
>    * i915_perf_ioctl - support ioctl() usage with i915 perf stream FDs
>    * @stream: An i915 perf stream
> @@ -2879,6 +2901,8 @@ static long i915_perf_ioctl_locked(struct i915_perf_stream *stream,
>   	case I915_PERF_IOCTL_DISABLE:
>   		i915_perf_disable_locked(stream);
>   		return 0;
> +	case I915_PERF_IOCTL_CONFIG:
> +		return i915_perf_config_locked(stream, arg);

For REMOVE_CONFIG we passed a pointer to an u64, not sure whether we 
should reuse the same pattern here?

I don't mind the current version.


-Lionel

>   	}
>   
>   	return -EINVAL;
> @@ -4017,7 +4041,15 @@ void i915_perf_fini(struct drm_i915_private *i915)
>    */
>   int i915_perf_ioctl_version(void)
>   {
> -	return 1;
> +	/*
> +	 * 1: Initial version
> +	 *   I915_PERF_IOCTL_ENABLE
> +	 *   I915_PERF_IOCTL_DISABLE
> +	 *
> +	 * 2: Added runtime modification of OA config.
> +	 *   I915_PERF_IOCTL_CONFIG
> +	 */
> +	return 2;
>   }
>   
>   #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 0c7b2815fbf1..5e66f7c60261 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -1932,6 +1932,16 @@ struct drm_i915_perf_open_param {
>    */
>   #define I915_PERF_IOCTL_DISABLE	_IO('i', 0x1)
>   
> +/**
> + * Change metrics_set captured by a stream.
> + *
> + * Will not take effect until the stream is restart, or upon the next
> + * execbuf when attached to a specific context.
> + *
> + * This ioctl is available in perf revision 2.
> + */
> +#define I915_PERF_IOCTL_CONFIG	_IO('i', 0x2)
> +
>   /**
>    * Common to all i915 perf records
>    */


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