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  1. Bug #1580792
  2. Comment #3

Comment 3 for bug 1580792

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Daniel van Vugt (vanvugt) wrote : Re: Unity8 on Intel Atoms performs poorly

Adding INTEL_DEBUG=perf to /etc/environment has seemingly explained the problems. Atoms are falling back to software rendering(!), which is theoretically easy to avoid. Here's a summary of what I get in unity8.log on an Atom N270:

PROBLEM:
old_intel_miptree_blit: Can't use hardware blitter from MESA_FORMAT_B8G8R8A8_UNORM to MESA_FORMAT_A_UNORM8, falling back.
intelCopyTexSubImage - fallback to swrast
CAUSE: Unknown

PROBLEM:
i915_program_error: Exceeded max ALU instructions (76 out of 64)
ENTER FALLBACK 10000: Program
CAUSE: GLSL shaders are approximately 18% larger than the hardware supports.

PROBLEM:
ENTER FALLBACK 10000: Program
LEAVE FALLBACK Program
[PERFORMANCE]: Last frame took 2643 ms to render.
CAUSE: Same as previous issue. Reused a program that ran in software.

Interestingly mir_demo_client_eglplasma has the same issues (bug 1583532) but it sounds like that's easily fixable.