Re: [PATCH i-g-t] i915/gem_map_gtt: Escape from slow forked GTT access

From: Mika Kuoppala <mika.kuoppala@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH i-g-t] i915/gem_map_gtt: Escape from slow forked GTT access
Date: Tue, 24 Sep 2019 16:09:53 +0300	[thread overview]
Message-ID: <87d0fpzvq6.fsf@gaia.fi.intel.com> (raw)
In-Reply-To: <20190924121821.31277-1-chris@chris-wilson.co.uk>

Chris Wilson <chris@chris-wilson.co.uk> writes:

> Beware the slithy t'oves.
>
> Forked GTT access on icl is notoriously slow, so rather than spend an
> eternity checking the whole object, check for a completion event after
> handling the pagefault. It's is the race of the pagefault vs reset that
> we care most about, and we expect the bug to result in the pagefault
> being blocked indefinitely, so checking afterwards does not reduce
> coverage.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>

Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

> ---
>  tests/i915/gem_mmap_gtt.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/tests/i915/gem_mmap_gtt.c b/tests/i915/gem_mmap_gtt.c
> index 0428a1372..91da5a37b 100644
> --- a/tests/i915/gem_mmap_gtt.c
> +++ b/tests/i915/gem_mmap_gtt.c
> @@ -602,6 +602,9 @@ test_hang(int fd)
>  
>  				gtt[0][x] = patterns[next_pattern];
>  				gtt[1][x] = patterns[next_pattern];
> +
> +				if (READ_ONCE(control->done))
> +					break;
>  			}
>  
>  			last_pattern = next_pattern;
> -- 
> 2.23.0
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx