| Message ID | 1465391238-32737-1-git-send-email-mika.kuoppala@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jun 08, 2016 at 04:07:17PM +0300, Mika Kuoppala wrote: > 0xffffffff as an illegal command confuses the command execution > on gen9 so that the next BB start will get ignored, causing a runaway > head past the bb end. This delays the hang detection substantially > as hangcheck then observes only a non progressing seqno. > > Omit the bad instruction on gen8+ and rely on the chained batch > loop to cause a deterministic hang. Make the chained bb start > to jump straight into bb start, omitting the MI_NOOP or the bad > instruction on subsequent passes. This makes the acthd sampling > to hit more reliably to the same value, as the loop is smaller, > making the head appear to be 'more stuck'. You could note that BB(addr | 4) is also illegal. gen2+ requires 8 byte alignment, ilk requires 64 byte. > References: https://bugs.freedesktop.org/show_bug.cgi?id=92715 > Cc: Chris Wilson <chris@chris-wilson.co.uk> > Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> -Chris
diff --git a/lib/igt_gt.c b/lib/igt_gt.c index 95d74a0cfeae..adb4b95bb913 100644 --- a/lib/igt_gt.c +++ b/lib/igt_gt.c @@ -181,16 +181,22 @@ igt_hang_ring_t igt_hang_ctx(int fd, exec.relocs_ptr = (uintptr_t)&reloc; memset(b, 0xc5, sizeof(b)); - b[0] = 0xffffffff; + len = 2; - if (intel_gen(intel_get_drm_devid(fd)) >= 8) + if (intel_gen(intel_get_drm_devid(fd)) >= 8) { + b[0] = MI_NOOP; len++; + } else { + b[0] = 0xffffffff; + } + b[1] = MI_BATCH_BUFFER_START | (len - 2); b[1+len] = MI_BATCH_BUFFER_END; b[2+len] = MI_NOOP; gem_write(fd, exec.handle, 0, b, sizeof(b)); reloc.offset = 8; + reloc.delta = 4; reloc.target_handle = exec.handle; reloc.read_domains = I915_GEM_DOMAIN_COMMAND;
0xffffffff as an illegal command confuses the command execution on gen9 so that the next BB start will get ignored, causing a runaway head past the bb end. This delays the hang detection substantially as hangcheck then observes only a non progressing seqno. Omit the bad instruction on gen8+ and rely on the chained batch loop to cause a deterministic hang. Make the chained bb start to jump straight into bb start, omitting the MI_NOOP or the bad instruction on subsequent passes. This makes the acthd sampling to hit more reliably to the same value, as the loop is smaller, making the head appear to be 'more stuck'. References: https://bugs.freedesktop.org/show_bug.cgi?id=92715 Cc: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com> --- lib/igt_gt.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)