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On 04/21/2017 03:12 AM, Nicholas Nethercote wrote:<br>
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<div>Judging from the incoming flow of bug reports, the number
of people using the Gecko Profiler has increased in the last
week or two. I take this as a good sign that it's being used
increasingly heavily for Quantum Flow work, which is good.<br>
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Yes, indeed. I should also say that this is definitely due to the
hard work of everyone working on improving it both the backend side
and on the UI side (including you!) It's safe to say that this push
on performance could not have happened without the Gecko Profiler,
so thanks to everyone who keeps making it better.<br>
<br>
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cite="mid:CAEXw-AANG78ZkMC3GXG_mjdcNv-pvVAPyXa5pv3cV6OeQcN2pA@mail.gmail.com"
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<div><br>
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<div>Nick<br>
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<div class="gmail_extra"><br>
<div class="gmail_quote">On Fri, Apr 21, 2017 at 4:25 PM, Ehsan
Akhgari <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:ehsan.akhgari@gmail.com" target="_blank">ehsan.akhgari@gmail.com</a>></span>
wrote:<br>
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<div>Hi everyone,</div>
<div><br>
</div>
<div>I would like to share some updates about some of the
ongoing performance related work.<br>
</div>
<div><br>
</div>
<div>We have started looking at the native stack traces
that are submitted through telemetry from the Background
Hang Reports that take more than 8 seconds. (We were
hoping to have been able to <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1346415"
target="_blank">reduce this threshold to 256ms</a> for
a while now, but the road has been bumpy -- but this
should land really soon now!) Michael Layzell put
together a telemetry analysis job that creates a
symbolicated version of this data here: <a
moz-do-not-send="true"
href="https://people-mozilla.org/%7Emlayzell/bhr/"
target="_blank">https://people-mozilla.org/~<wbr>mlayzell/bhr/</a>.
For example, <a moz-do-not-send="true"
href="https://people-mozilla.org/%7Emlayzell/bhr/20170405.html"
target="_blank">this</a> is the latest generated
report. The grouping of this data is unfortunate, since
the data is collected based on the profiler pseudo-stack
labels, which is captured after 128ms, and then native
stack (if the hang continues for 8 seconds) gets
captured after that, so the pseudo-stack and the native
stack may or may not correspond, and this grouping also
doesn't help going through the list of native stacks and
triage them more effectively. Work is under way to <a
moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1344003"
target="_blank">create a nice dashboard</a> out of
this data, but in the mean time this is an area where we
could really use all of the help that we can get. If
you have some time, it would be really nice if you can
take a look at this data and see if you can make sense
of some of these call stacks and find some useful bug
reports out of them. If you do end up filing bugs,
these are super important bugs to work on, so please
make sure you add "[qf]" to the status whiteboard so
that we can track the bug.</div>
<div><br>
</div>
<div>Another item worthy of highlight is Mike Conley's <a
moz-do-not-send="true"
href="https://mikeconley.github.io/ohnoreflow/"
target="_blank">Oh No! Reflow! add-on</a>. Don't let
the simple web page behind this link deceive you, this
add-on is really awesome! It generates a beep every
time that a long running reflow happens in the browser
UI (which, of course, you get to turn off when you don't
need to hunt for bugs!), and it logs the sync reflows
that happened alongside the JS call stack to the code
that triggered them, and it also gives you a single link
that allows you to quickly file a bug with all of the
right info in it, pre-filled! In fact you can see the <a
moz-do-not-send="true"
href="https://bugzilla.mozilla.org/buglist.cgi?quicksearch=sw%3A%22%5Bohnoreflow%5D%22&list_id=13547427"
target="_blank">list of already filed bugs</a> through
this add-on!</div>
<div><br>
</div>
<div>Another issue that I want to bring up is the [qf:p1]
bugs. As you have noticed, there are a lot of them.
:-) It is possible that some of these bugs aren't
important to work on, for example because they only
affect edge case conditions that affects a super small
subset of users and that wasn't obvious when the bug was
triaged. In some other cases it may turn out that
fixing the bug requires massive amounts of work that is
unreasonable to do in the amount of time we have, or
that the right people for it are doing more important
work and can't be interrupted, and so on. Whatever the
issue is, whether the bug was mis-triaged, or can't be
fixed, please make sure to raise it on the bug! In
general the earlier these issues are uncovered the
better it is, because everyone can focus their time on
more important work. I wanted to make sure that this
wasn't lost in all of the rush around our communication
for Quantum Flow, my apologies if this hasn't been clear
before.</div>
<div><br>
</div>
<br>
<div>On to the acknowledgement section, I hope I'm not
forgetting to mention anyone's name here!</div>
<div><br>
</div>
<div>
<ul>
<li>Bas Schouten made it so that we <a
moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1352442"
target="_blank">don't clear the compositor
background immediately before drawing into it</a>.
This made some painting and scrolling related
benchmarks <a moz-do-not-send="true"
href="https://treeherder.mozilla.org/perf.html#/alerts?id=5801"
target="_blank">faster</a>, and fixed a <a
moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1330814"
target="_blank">flickering issue</a> in the mean
time!</li>
<li>Mason Chang made the <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1351733"
target="_blank">Youtube settings widget less janky</a>
on Windows with D2D when the video is fullscreen.</li>
<li>David Baron made the flushes caused by the code
that watches your mouse to know which side of the
window to put the status bar when you hover a link <a
moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1307134"
target="_blank">less severe</a>.</li>
<li>Neil Deakin <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1334635"
target="_blank">removed a synchronous layout flush</a>
that used to happen when closing a window which
would slow down the window going away.</li>
<li>Dão Gottwald <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1345315"
target="_blank">removed some obsolete tab
animation telemetry</a> which could slow down tab
animations (yes!). Dão also <a
moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1356655"
target="_blank">removed a synchronous layout flush</a>
which could slow down detaching a tab into a new
window and he also lazified some code to <a
moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1356663"
target="_blank">avoid some more layout flushes</a>
which were related to the status panel.</li>
<li>Markus Stange made <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=830990"
target="_blank">the Gecko Profiler not kill your
battery after you stop profiling</a>, and also
made it so that <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1346592"
target="_blank">once you start profiling a thread,
you can actually stop profiling it</a>.</li>
<li>Michael Layzell <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1352684"
target="_blank">excluded some common file JS file
extensions</a> from the expensive computation that
we run on Windows to determine the mimetype of a
file from its extension.</li>
<li>Kris Maglione made it possible to <a
moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1314861"
target="_blank">load add-on SDK modules lazily</a>.
He also made <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1317697"
target="_blank">loading ExtensionContent.jsm lazy</a>.
These two changes together (but probably mostly the
former) showed <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1314861#c52"
target="_blank">great improvements on Talos</a>.
This is even true for users without any add-ons
using the add-on SDK since these modules are also
used in our internal code.</li>
<li>Robert Helmer <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1356676"
target="_blank">created a Go Faster add-on</a> to
quickly deploy the fix of <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1353216"
target="_blank">bug 1353216</a> to Firefox 52
users even before they upgrade to Firefox 53 which
includes the fix!</li>
<li>Edouard Oger made <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1350613"
target="_blank">Firefox Sync UI code cache the
DateTimeFormat objects</a> where possible.</li>
<li>Alastor Wu made some Fennec media controls code
that could be expensive <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348803"
target="_blank">not run on Firefox desktop</a>.</li>
<li>Makoto Kato <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1352882"
target="_blank">added a cache for document encoder
objects used by TextEditor</a>, in order to
improve the performance of setting the value of
HTMLInputElement.value.</li>
<li>Tom Schuster <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1344469"
target="_blank">optimized Object.hasOwnProperty()</a>.
This is a commonly used JavaScript built-in on real
web pages, really nice optimization to have!</li>
<li>Florian Quèze <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1353563"
target="_blank">removed a synchronous layout flush</a>
that used to happen when displaying each item in the
awesome bar. He improved the awesomebar even more
by <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1312999"
target="_blank">caching the one-off search buttons
instead of regenerating them every time we open
the popup</a>. Furthermore, he ensured that <a
moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1349742"
target="_blank">we don't pay the cost of
initializing UITour.jsm for pages that do not
display a UI tour</a>.</li>
<li>Wei-Cheng Pan <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1344893"
target="_blank">added telemetry probes for
navigation timings and time to first byte measures</a>.</li>
<li>Shu-yu Guo <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348134"
target="_blank">improved the timing of script
source compression by delaying it until GC</a>.
Previously we used to do this when parsing
JavaScript (on a separate thread) which is wasteful
because it would mean that we'd have to decompress
the compressed source during page load sometimes,
and also burning needless CPU cycles during JS
parsing isn't wise.</li>
<li>J. Ryan Stinnett <a moz-do-not-send="true"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=1346854"
target="_blank">made the Developer Toolbar not
create a network listener for every single tab
that you have open</a>. Besides perf wins, this
means fewer OOM crashes too!</li>
</ul>
<div>Thanks for reading! Until next time, happy
hacking!<span class="HOEnZb"><font color="#888888"><br>
</font></span></div>
</div>
<span class="HOEnZb"><font color="#888888">
<div><br>
-- <br>
<div class="m_8320608157022559052gmail_signature">
<div dir="ltr">Ehsan<br>
</div>
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