Quoting Lionel Landwerlin (2017-08-29 11:58:57)
> This allows us to deploy new configurations without touching the
> kernel.
>
> Signed-off-by: Lionel Landwerlin <lionel.g.landwer...@intel.com>
> ---
> src/mesa/drivers/dri/i965/brw_performance_query.c | 97
> ++++++++++++++++++++++-
> 1 file changed, 96 insertions(+), 1 deletion(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_performance_query.c
> b/src/mesa/drivers/dri/i965/brw_performance_query.c
> index 4b585c95b7d..901cbb464e9 100644
> --- a/src/mesa/drivers/dri/i965/brw_performance_query.c
> +++ b/src/mesa/drivers/dri/i965/brw_performance_query.c
> @@ -1807,6 +1807,96 @@ read_sysfs_drm_device_file_uint64(struct brw_context
> *brw,
> return read_file_uint64(buf, value);
> }
>
> +static bool
> +kernel_has_dynamic_config_support(int drm_fd, const char *sysfs_dev_dir)
> +{
> + struct drm_i915_perf_oa_config config;
> + const char *uuid = "01234567-0123-0123-0123-0123456789ab";
> + uint32_t mux_regs[] = { 0x9888 /* NOA_WRITE */, 0x0 };
> + char config_path[256];
> + struct stat sb;
> + uint64_t config_id;
> + int ret;
> +
> + snprintf(config_path, sizeof(config_path),
> + "%s/metrics/%s/id", sysfs_dev_dir, uuid);
> +
> + if (stat(config_path, &sb) == 0) {
> + if (!read_file_uint64(config_path, &config_id))
> + return false;
> +
> + if (ioctl(drm_fd, DRM_IOCTL_I915_PERF_REMOVE_CONFIG, &config_id) == 0)
> + return true;
So you acknowledge the race condition with another process also doing
the same test, or worse if they genuinely used that uuid for an actual
config.
> + }
> +
> + memset(&config, 0, sizeof(config));
> + memcpy(config.uuid, uuid, sizeof(config.uuid));
> +
> + config.n_mux_regs = 1;
> + config.mux_regs_ptr = (uintptr_t) mux_regs;
> +
> + /* Create a new config */
> + ret = ioctl(drm_fd, DRM_IOCTL_I915_PERF_ADD_CONFIG, &config);
> + if (ret < 0)
> + return false;
A trick you may like to try is to create an invalid config that
generates something other than EINVAL so that you can then distinguish
with the non-existent ioctl cmd error. Since you reserved id=0 for
invalid, a good choice would be
static bool has_dyn_config() {
uint64_t config_id = 0;
return sys_ioctl(drm_fd, DRM_IOCTL_I915_PERF_REMOVE_CONFIG, &config_id)
== -ENOENT;
}
-Chris
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