Bug 229326

I know this will incite heckling and a tomato thrown at me but I also noted that even the Windows build of firefox uses VC's -O1 (optimize code for minimum size), similar to Android's -Oz optimization in about:buildconfig. I wouldn't advocate for -Oz over -O2, but I am suggesting -O3 is not the most desirable optimization level, particularly for such an already large application like firefox, where a marginal gain in corner cases cannot overcome larger binary size that ultimately slows down overall loading and execution. But again, if anyone has browser benchmarks I would be very interested to study them.

Comment 2 Jan Beich 2018-06-26 00:07:39 UTC

-O3 is enabled by default because Mozilla uses it on macOS which is like FreeBSD a Clang platform. FreeBSD Port allows to override -O3 via CFLAGS in make.conf as only the last -O<n> matters.

(In reply to Kenneth Salerno from comment #0)
> laptop with inadequate RAM

Firefox is supposed to take advantage of mozjemalloc to keep memory usage low. Unfortunately, it hasn't been ported to FreeBSD despite originating from there. If Stylo performance isn't very important try the following workaround:

  # jemalloc4 tunning before https://bugzilla.mozilla.org/show_bug.cgi?id=1363992
  $ MALLOC_CONF="narenas:1,tcache:false" firefox ...

> Fedora Linux ... GCC7

Distro builds may use different flags. Try looking at Mozilla build logs from "opt" jobs in https://treeherder.mozilla.org/#/jobs?repo=mozilla-release

Another option is to extract a binary:

$ fetch https://download.cdn.mozilla.net/pub/firefox/releases/61.0/linux-x86_64/en-US/firefox-61.0.tar.bz2
$ tar xkf firefox-61.0.tar.bz2
$ (cd firefox; tar xUf omni.ja)
$ (cd firefox/browser; tar xUf omni.ja)
$ fgrep -B2 -- -O3 firefox/chrome/toolkit/content/global/buildconfig.html
      <td>/builds/worker/workspace/build/src/gcc/bin/g++</td>
      <td>6.4.0</td>
      <td>-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -Wall -Wempty-body -Wignored-qualifiers -Woverloaded-virtual -Wpointer-arith -Wsign-compare -Wtype-limits -Wunreachable-code -Wwrite-strings -Wno-invalid-offsetof -Wduplicated-cond -Wno-error=maybe-uninitialized -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wno-error=coverage-mismatch -Wno-error=free-nonheap-object -Wformat -D_GLIBCXX_USE_CXX11_ABI=0 -fno-sized-deallocation -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fno-exceptions -fno-strict-aliasing -fno-rtti -ffunction-sections -fdata-sections -fno-exceptions -fno-math-errno -pthread -pipe -g -O3 -fomit-frame-pointer</td>

(In reply to Jan Beich from comment #2)
> FreeBSD Port allows to override -O3 via CFLAGS in make.conf as only the last -O<n> matters.

make.conf is read before Mk/bsd.gecko.mk, so the CFLAGS+=-O3 is ultimately the last parameter and thus forced. The only way around it short of hacking Mk/bsd.gecko.mk is to unset OPTIMIZED_CFLAGS, but then this has the side-effect of passing configure --disable-optimize which adds the flag -fno-omit-frame-pointer which increases function call time if you have no intention of debugging. 

I'm not sure what a compromise could be unless we introduce another port option (disabled by default to not upset people) to optimize for size? See attached patch.

Created attachment 194687 [details]
patch to add new option to www/firefox to optimize for minimum size

Created attachment 194688 [details]
patch to add new option to www/firefox to optimize for minimum size

removed a script redundancy I had

Created attachment 194689 [details]
patch to add new option to www/firefox to optimize for minimum size

third time is the charm.

Created attachment 194733 [details]
patch to add new option to www/firefox to optimize for minimum size

Apparently -Oz makes firefox segfault, switching to -Os. Results on my laptop: virtual mem utilization for firefox went from >1.4G to 500M, improving responsiveness.

Comment 8 Walter Schwarzenfeld 2019-03-02 04:02:57 UTC

ping!