Ah, something I forgot to highlight in the cover letter is an issue with the "drm/i915: don't whitelist oacontrol in cmd parser" patch in this series...
I was hoping that I could get away with this without breaking any existing userspace, since the only userspace I know that attempts to configure OACONTROL via LRIs is Mesa which attempts to verify that it can successfully write to OACONTROL before exposing its current INTEL_performance_query implementation, and it seems like it should gracefully handle a failure here as if the command parser where disabled.
Incidentally, entirely disabling the command parser seems to work; but removing just OACONTROL seems to cause trouble.
Hopefully I can get a better understanding of what's going on here, though I can at least confirm the problem is triggered via the intel_extensions.c:can_write_oacontrol() check in Mesa. Bypassing this check (with a true or false status) is enough to get gnome-shell running again.
This could be a fiddly compatibility issue if it turns out to not be possible to remove OACONTROL from the cmd parser white list. One basic problem that stems from here is that whenever a GL application starts and this OACONTROL check is done it ends up resetting OACONTROL to zero which disables the OA unit which may be in use via the i915 perf interface.Regards,
- Robert
On Wed, Apr 20, 2016 at 3:23 PM, Robert Bragg <robert@xxxxxxxxxxxxx> wrote:
I've been working on some i-g-t tests for this new interface and while I still
have some more tests to write, it still seemed worth sending out another updated
series in the mean time.
Firstly this includes updates based on Emil's previous comments.
Then there have been a few issue hit while writing tests:
* It seems it can take a fairly long time for the MUX config to apply after
the register writes have finished, and now the driver inserts a delay after
configuration, before enabling periodic sampling.
* I've found that sometimes the HW tail pointer can get ahead of OA buffer
writes, especially with higher sampling frequencies, and so now the driver
maintains a margin behind the HW tail pointer to ensure the most recent
reports have some time to land before attempting to copy them to userspace.
* As a sanity check that a report is valid before it's copied to userspace the
driver checks the report-id field != 0
* The _BUFFER_OVERFLOW record has been replaced with a _BUFFER_LOST record with
more specific semantics.
* Since we can't clear the overflow status on Haswell while periodic sampling
is enabled, if an overflow occurs we now restart the unit.
* The maximum OA periodic sampling exponent is now 31
* We verify the head/tail pointers read back from HW look sane before using as
offsets to read reports from the OA buffer. We reset the HW if they look bad.
For reference the work-in-progress i-g-t tests can be found here:
https://github.com/rib/intel-gpu-tools
branch = wip/rib/i915-perf-tests
or browsed here:
https://github.com/rib/intel-gpu-tools/commits/wip/rib/i915-perf-tests
Also for reference these patches can be fetched from here:
https://github.com/rib/linux
branch = wip/rib/oa-2016-04-19-nightly
Regards,
- Robert
Robert Bragg (9):
drm/i915: Add i915 perf infrastructure
drm/i915: rename OACONTROL GEN7_OACONTROL
drm/i915: don't whitelist oacontrol in cmd parser
drm/i915: Add 'render basic' Haswell OA unit config
drm/i915: Enable i915 perf stream for Haswell OA unit
drm/i915: advertise available metrics via sysfs
drm/i915: Add dev.i915.perf_event_paranoid sysctl option
drm/i915: add oa_event_min_timer_exponent sysctl
drm/i915: Add more Haswell OA metric sets
drivers/gpu/drm/i915/Makefile | 4 +
drivers/gpu/drm/i915/i915_cmd_parser.c | 33 +-
drivers/gpu/drm/i915/i915_dma.c | 8 +
drivers/gpu/drm/i915/i915_drv.h | 155 ++++
drivers/gpu/drm/i915/i915_gem_context.c | 24 +-
drivers/gpu/drm/i915/i915_oa_hsw.c | 658 ++++++++++++++
drivers/gpu/drm/i915/i915_oa_hsw.h | 38 +
drivers/gpu/drm/i915/i915_perf.c | 1439 +++++++++++++++++++++++++++++++
drivers/gpu/drm/i915/i915_reg.h | 340 +++++++-
include/uapi/drm/i915_drm.h | 133 +++
10 files changed, 2795 insertions(+), 37 deletions(-)
create mode 100644 drivers/gpu/drm/i915/i915_oa_hsw.c
create mode 100644 drivers/gpu/drm/i915/i915_oa_hsw.h
create mode 100644 drivers/gpu/drm/i915/i915_perf.c
--
2.7.1
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