Re: [PATCH] prime_self_import: Assure no pending requests before object counting

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Nov 01, 2013 at 12:53:42PM +0000, oscar.mateo@intel.com wrote:
> From: Oscar Mateo <oscar.mateo@intel.com>
> 
> We don't want a previously used object to be freed in the middle of a
> before/after object counting operation (or we would get a "-1 objects
> leaked" message). We have seen this happening, e.g., when a context
> from a previous run dies, but its backing object is alive waiting for
> a retire_work to kick in.
> 
> Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
> Cc: Ben Widawsky <ben@bwidawsk.net>

Nice catch. Should we do this in general as part of our gem_quiescent_gpu
helper? All i-g-t testcase are written under the assumption that they
completel own the gpu and that the gtt is completely empty besides the few
driver-allocated and pinned objects. So trying really hard to get rid of
any residual stuff sounds like a good idea.

Then we could just add a call to gem_quiescent_gpu to the get_object_count
function.

Care to rework the patch a bit and make sure it all still works?

Thanks, Daniel

> ---
>  tests/prime_self_import.c |   29 +++++++++++++++++++++++++++--
>  1 file changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/prime_self_import.c b/tests/prime_self_import.c
> index 481a809..e48abd1 100644
> --- a/tests/prime_self_import.c
> +++ b/tests/prime_self_import.c
> @@ -211,6 +211,25 @@ static void test_with_one_bo(void)
>  	check_bo(fd2, handle_import1, fd2, handle_import1);
>  }
>  
> +static void retire_requests(void)
> +{
> +	char fname[FILENAME_MAX];
> +	int drop_caches_fd;
> +	const char *data = "0x4";
> +
> +	snprintf(fname, FILENAME_MAX, "%s/%i/%s",
> +		 "/sys/kernel/debug/dri", drm_get_card(),
> +		 "i915_gem_drop_caches");
> +
> +	drop_caches_fd = open(fname, O_WRONLY);
> +
> +	if (drop_caches_fd >= 0)
> +	{
> +		write(drop_caches_fd, data, strlen(data) + 1);
> +		close(drop_caches_fd);
> +	}
> +}
> +
>  static int get_object_count(void)
>  {
>  	FILE *file;
> @@ -252,10 +271,13 @@ static void test_reimport_close_race(void)
>  	pthread_t *threads;
>  	int r, i, num_threads;
>  	int fds[2];
> -	int obj_count = get_object_count();
> +	int obj_count;
>  	void *status;
>  	uint32_t handle;
>  
> +	retire_requests();
> +	obj_count = get_object_count();
> +
>  	num_threads = sysconf(_SC_NPROCESSORS_ONLN);
>  
>  	threads = calloc(num_threads, sizeof(pthread_t));
> @@ -330,9 +352,12 @@ static void test_export_close_race(void)
>  	pthread_t *threads;
>  	int r, i, num_threads;
>  	int fd;
> -	int obj_count = get_object_count();
> +	int obj_count;
>  	void *status;
>  
> +	retire_requests();
> +	obj_count = get_object_count();
> +
>  	num_threads = sysconf(_SC_NPROCESSORS_ONLN);
>  
>  	threads = calloc(num_threads, sizeof(pthread_t));
> -- 
> 1.7.9.5
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch