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<body><span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [CI] igt@perf_pmu@semaphore-wait-[vcs0|vecs0|bcs0] - Failed assertion: (double)(val[1] - val[0]) <= (1.0 + (tolerance)) * (double)(slept) && (double)(val[1] - val[0]) >= (1.0 - (tolerance)) * (double)(slept)"
href="https://bugs.freedesktop.org/show_bug.cgi?id=104013">bug 104013</a>
<br>
<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
</td>
</tr>
<tr>
<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>FIXED
</td>
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [CI] igt@perf_pmu@semaphore-wait-[vcs0|vecs0|bcs0] - Failed assertion: (double)(val[1] - val[0]) <= (1.0 + (tolerance)) * (double)(slept) && (double)(val[1] - val[0]) >= (1.0 - (tolerance)) * (double)(slept)"
href="https://bugs.freedesktop.org/show_bug.cgi?id=104013#c5">Comment # 5</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [CI] igt@perf_pmu@semaphore-wait-[vcs0|vecs0|bcs0] - Failed assertion: (double)(val[1] - val[0]) <= (1.0 + (tolerance)) * (double)(slept) && (double)(val[1] - val[0]) >= (1.0 - (tolerance)) * (double)(slept)"
href="https://bugs.freedesktop.org/show_bug.cgi?id=104013">bug 104013</a>
from <span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span></b>
<pre>commit c7b20c950276a41badd994324e1983760e44842b
Author: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
Date: Sat Dec 2 00:14:52 2017 +0000
igt/perf_pmu: Tighten semaphore-wait measurement
Record the before/after semaphore-wait values around the sleep to try to
reduce the inaccuracy from scheduler delays. Previously, the samples
were taken before submitting the batch and then after synchronising its
completion. The measurement will then be the total that the semaphore
was being sampled, but with the extra syscalls intervening may have
drifted from the sleep duration. To further reduce the disparity, wait
for the batch to start executing before taking our samples.
References: <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [CI] igt@perf_pmu@semaphore-wait-[vcs0|vecs0|bcs0] - Failed assertion: (double)(val[1] - val[0]) <= (1.0 + (tolerance)) * (double)(slept) && (double)(val[1] - val[0]) >= (1.0 - (tolerance)) * (double)(slept)"
href="show_bug.cgi?id=104013">https://bugs.freedesktop.org/show_bug.cgi?id=104013</a>
Signed-off-by: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
Cc: Tvrtko Ursulin <<a href="mailto:tvrtko.ursulin@intel.com">tvrtko.ursulin@intel.com</a>>
Reviewed-by: Tvrtko Ursulin <<a href="mailto:tvrtko.ursulin@intel.com">tvrtko.ursulin@intel.com</a>>
Once again, hopefully the last tweak required.</pre>
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