Commit dc342156 authored by Tvrtko Ursulin's avatar Tvrtko Ursulin Committed by Jani Nikula

drm/i915: Fix context runtime accounting

When considering whether to mark one context as stopped and another as
started we need to look at whether the previous and new _contexts_ are
different and not just requests. Otherwise the software tracked context
start time was incorrectly updated to the most recent lite-restore time-
stamp, which was in some cases resulting in active time going backward,
until the context switch (typically the heartbeat pulse) would synchronise
with the hardware tracked context runtime. Easiest use case to observe
this behaviour was with a full screen clients with close to 100% engine
load.
Signed-off-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: bb6287cb ("drm/i915: Track context current active time")
Cc: <stable@vger.kernel.org> # v5.19+
Reviewed-by: default avatarMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230320151423.1708436-1-tvrtko.ursulin@linux.intel.com
[tursulin: Fix spelling in commit msg.]
(cherry picked from commit b3e70051)
Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
parent dc30c011
...@@ -2018,6 +2018,8 @@ process_csb(struct intel_engine_cs *engine, struct i915_request **inactive) ...@@ -2018,6 +2018,8 @@ process_csb(struct intel_engine_cs *engine, struct i915_request **inactive)
* inspecting the queue to see if we need to resumbit. * inspecting the queue to see if we need to resumbit.
*/ */
if (*prev != *execlists->active) { /* elide lite-restores */ if (*prev != *execlists->active) { /* elide lite-restores */
struct intel_context *prev_ce = NULL, *active_ce = NULL;
/* /*
* Note the inherent discrepancy between the HW runtime, * Note the inherent discrepancy between the HW runtime,
* recorded as part of the context switch, and the CPU * recorded as part of the context switch, and the CPU
...@@ -2029,9 +2031,15 @@ process_csb(struct intel_engine_cs *engine, struct i915_request **inactive) ...@@ -2029,9 +2031,15 @@ process_csb(struct intel_engine_cs *engine, struct i915_request **inactive)
* and correct overselves later when updating from HW. * and correct overselves later when updating from HW.
*/ */
if (*prev) if (*prev)
lrc_runtime_stop((*prev)->context); prev_ce = (*prev)->context;
if (*execlists->active) if (*execlists->active)
lrc_runtime_start((*execlists->active)->context); active_ce = (*execlists->active)->context;
if (prev_ce != active_ce) {
if (prev_ce)
lrc_runtime_stop(prev_ce);
if (active_ce)
lrc_runtime_start(active_ce);
}
new_timeslice(execlists); new_timeslice(execlists);
} }
......
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