Re: [PATCH 1/2] intel_get_llc_size: Small tool to query LLC size

[Chad Versace <chad.versace@linux.intel.com>]

On 07/11/2013 11:53 AM, Ben Widawsky wrote:
> v2: Use the new param
>
> CC: Chad Versace <chad.versace@linux.intel.com>
> CC: Bryan Bell <bryan.j.bell@intel.com>
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> ---
>   tools/Makefile.am          |  1 +
>   tools/intel_get_llc_size.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++
>   2 files changed, 59 insertions(+)
>   create mode 100644 tools/intel_get_llc_size.c
>
> diff --git a/tools/Makefile.am b/tools/Makefile.am
> index 2519169..a064b65 100644
> --- a/tools/Makefile.am
> +++ b/tools/Makefile.am
> @@ -9,6 +9,7 @@ bin_PROGRAMS = 				\
>   	intel_bios_dumper 		\
>   	intel_bios_reader 		\
>   	intel_error_decode 		\
> +	intel_get_llc_size 		\
>   	intel_gpu_top 			\
>   	intel_gpu_time 			\
>   	intel_gtt 			\
> diff --git a/tools/intel_get_llc_size.c b/tools/intel_get_llc_size.c
> new file mode 100644
> index 0000000..498e252
> --- /dev/null
> +++ b/tools/intel_get_llc_size.c
> @@ -0,0 +1,58 @@
> +/*
> + * Copyright © 2013 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
> + * DEALINGS IN THE SOFTWARE.
> + *
> + */
> +
> +#include <sys/ioctl.h>
> +#include "drmtest.h"
> +#include "i915_drm.h"
> +
> +#define LOCAL__I915_PARAM_LLC_SIZE 27
> +static int get_llc_size(int fd)
> +{
> +	struct drm_i915_getparam gp;
> +	int size;
> +
> +	gp.param = LOCAL__I915_PARAM_LLC_SIZE;
> +	gp.value = &size;
> +
> +	if (ioctl(fd, DRM_IOCTL_I915_GETPARAM, &gp, sizeof(gp)))
> +		return 0;
> +
> +	return size;
> +}
> +
> +int main(int argc, char **argv)
> +{
> +	int size, fd = drm_open_any();
> +
> +	size = get_llc_size(fd);
> +
> +	if (size == 0)
> +		fprintf(stdout, "Doesn't have LLC\n");
> +	else if (size == 1)
> +		fprintf(stdout, "Kernel is too old to determine LLC size\n");
> +	else
> +		fprintf(stdout, "LLC size = %dK\n", size>>10);

This if-tree looks wrong. If the kernel doesn't know about I915_PARAM_LLC_SIZE,
the ioctl returns -1, and get_llc_size() returns 0, and the if-tree prints the
wrong error.

How about making get_llc_size() return -1 on error? Or am I missing something here?

> +
> +	return 0;
> +}
>

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