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<b><a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - [SKL] (recoverable) GPU hangs in benchmarks using compute shaders with drm-tip v4.20-rc kernels"
href="https://bugs.freedesktop.org/show_bug.cgi?id=108820#c23">Comment # 23</a>
on <a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - [SKL] (recoverable) GPU hangs in benchmarks using compute shaders with drm-tip v4.20-rc kernels"
href="https://bugs.freedesktop.org/show_bug.cgi?id=108820">bug 108820</a>
from <span class="vcard"><a class="email" href="mailto:jakub@okonski.org" title="Jakub Okoński <jakub@okonski.org>"> <span class="fn">Jakub Okoński</span></a>
</span></b>
<pre>I'm trying to reduce the shader to bare-minimum that reproduces the hang, here
it is:
```
#version 450
layout (local_size_x = 65) in;
void main() {
if (gl_GlobalInvocationID.x >= 20) {
return;
}
barrier();
}
```
New piece of information is the early-return that is required to trigger the
hang. From this baseline shader, if I decrease local_size_x to 64, it works. Or
I can remove the if statement and it will also work. Or I can remove the
barrier() and it will also start to work. It seems to be a combination of these
that causes the hang. If I take away any piece from it, the problem goes away.
I'm attaching the debug info on this minimal shader.</pre>
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