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Craig, you're probably qualified best to answer this, as you already
did some steps to port to idf 4.0?<br>
<br>
<a class="moz-txt-link-freetext" href="https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/issues/360">https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/issues/360</a><br>
<br>
But I guess there have been quite some changes since 4.0 also. We'll
have to try and solve the issues one by one.<br>
<br>
Probably best to get for-v3.3 including the SIM7600 support stable
and merged into master first. Mark, I'll merge the heap change into
for-v3.3 next.<br>
<br>
Regards,<br>
Michael<br>
<br>
<br>
<div class="moz-cite-prefix">Am 04.09.21 um 21:52 schrieb Stephen
Casner:<br>
</div>
<blockquote type="cite"
cite="mid:alpine.OSX.2.21.9999.2109041244390.93068@auge.attlocal.net">
<pre class="moz-quote-pre" wrap="">Michael,
Thanks for performing this diagnosis and enhancement.
Has anyone analyzed the work required to move to current esp-idf? How
many things will break? I imagine the heap instrumentation I added
would be one of them. Perhaps we could divide up that work among
several developers. I would likely need to get another module,
though, because my current v3.0 bench unit without SPIRAM probably
wouldn't be usable.
-- Steve
On Sat, 4 Sep 2021, Michael Balzer wrote:
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">Everyone,
the poor JSON encoding performance reminded me of another issue we've had with
Duktape since integration: the overall slowly degrading performance of the
whole system over time.
I did some new analysis on this effect using the task monitoring, which showed
it's become worse lately up to the point where Duktape needs more than a
second to perform the garbage collection after just 24 hours of uptime. It
turned out this effect is also one of the major causes for the very bad JSON
encoding performance, i.e. needing up to 10 seconds for a simple object of 5 x
1440 values, and eating 15-20% of CPU time on a permanent base (instead of the
tolerable 5-6% right after boot).
Doing a "script reload" would help, but only temporarily and not near the
point of a freshly booted system.
I didn't find anything about such an effect for Duktape in general, so I
turned to examining possible ESP32 specific causes, and finally found the
culprit: the esp-idf memory management, or more precisely, it's issues with
fragmentation in SPIRAM. Duktape is probably one of the main fragmentation
drivers due to the nature of Javascript memory management (garbage
collection).
There has been some discussion on this by neoniousTR, who also was involved in
the SPIRAM bug hunt: <a class="moz-txt-link-freetext" href="https://www.esp32.com/viewtopic.php?t=8628">https://www.esp32.com/viewtopic.php?t=8628</a>
The dlmalloc adaptation of neoniousTR unfortunately isn't usable for us, as it
exceeds our available IRAM. It also was based on a much earlier esp-idf
release, and doesn't support the extensions and options we use.
Espressif have introduced a new memory manager to address these issues, but
only in esp-idf release 4.3. We'll need to go there one day, but that's
nothing we can do short term:
<a class="moz-txt-link-freetext" href="https://github.com/espressif/esp-idf/releases/tag/v4.3">https://github.com/espressif/esp-idf/releases/tag/v4.3</a> → "Heap: Switched heap
algorithm to one based on TLSF, improves performance especially when using a
high number of allocations in PSRAM"
So I've tried another option: I've removed the Duktape heap from the standard
system memory management. I've added a separate umm_malloc instance just for
the heap, which can work very fast because it doesn't need to take care of
locking or poisoning.
On Duktape startup, a fixed amount of SPIRAM gets allocated for the Javascript
heap. The amount is 512 KB by default, which should be sufficient for most
cases. I've added a configuration for this, config module duktape.heapsize,
and a meminfo command to provide some insight.
The results are:
* Overall Duktape speedup of at least factor 3, up to factor 8
* Garbage collection runs now need below 100 ms even with large
scripts running
* Duktape average CPU usage dropped to 1-2%
* Barely noticeable overall performance degradation after a week of
continuous operation
Of course, your mileage may vary, feedback is welcome.
It still degrades, which is kind of expected, as Duktape isn't the only system
component doing dynamic memory allocations.
I think esp-idf 4.3 may offer a significant overall performance increase for
us, just by replacing the current memory management by a more sophisticated
implementation.
As a side effect, JSON encoding is now much faster (by up to factor 8). CBOR
has become only about 30% faster, which is probably due to CBOR needing much
less memory allocations. CBOR is still factor 3 faster on average than JSON,
so still the preferred choice for storage & transmission.
Details & code:
<a class="moz-txt-link-freetext" href="https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/commit/1bcc8dd84405df81e61577a90909e7b43c25baa3">https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/commit/1bcc8dd84405df81e61577a90909e7b43c25baa3</a>
Note: there are three new Kconfig variables that need to be set to enable the
new Duktape memory management. The sdkconfig.default.hw31 includes the new
configuration, if doing a "make", simply accept all defaults.
Regards,
Michael
--
Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26</pre>
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<pre class="moz-quote-pre" wrap="">_______________________________________________
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</pre>
</blockquote>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26</pre>
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