# -*- mode: org; mode: org-edna; mode: visual-line; mode: flyspell; -*-

#+TITLE: Emacs 30.1 on Android: Termux vs. Android Linux Terminal
#+STARTUP: align

* Purpose and Motivation
[2025-03-08 Sat 18:21]

These are the results of running the elisp-benchmarks package against
two versions of emacs 30.1 on identical hardware, a Pixel 9 Pro XL
Android phone.  The reason for running the benchmark is to compare two
different runtime environments: one is Termux, which is thin
virtualization layer atop the Android underpinnings; the other is the
new Android Linux Terminal shipped in the Android 15 March 2025
feature drop, which is effectively a fully virtualized aarch64 Linux
subsystem running atop the Android operating system.

The comparison is interesting because the version of emacs 30.1
packaged by Termux explicitly lacks the native-compilation feature
built atop libgccjit, whereas the version of emacs 30.1 that I
self-compiled within the Android Linux Terminal includes the
native-comp library.

Will the extra indirection of the virtualization layer soak up all the
performance advantages offered by native elisp compilation?  Let's
find out!

* Methodology

I installed the elisp-benchmarks suite with the straight.el package
manager by running:

    M-x straight-use-package <ret> elisp-benchmarks <ret>

This invocation cloned the elisp-benchmarks repo from:

    https://github.com/emacs-straight/elisp-benchmarks.git

...as of commit d4f5245b778842941ab046bff3274804d5f529a3 .  On the
version of emacs packaged by termux, this byte-compiled the benchmarks
at installation time; on the self-compiled emacs this also generated
native-compiled files under ~/.emacs.d/eln-cache/... .  I waited for
the compilation process to fully complete before proceeding.

I then backgrounded emacs with C-z and, per the instructions in the
header of the elisp-benchmarks.el file itself, I ran:

    emacs -batch -l ~/.emacs.d/straight/repos/elisp-benchmarks/elisp-benchmarks.el -f elisp-benchmarks-run

The output of:

    (describe-variable 'system-configuration-options)
    (describe-variable 'system-configuration-features)

...for each emacs is as follows:

** system-configuration-options

*** termux emacs

    --disable-dependency-tracking
    --prefix=/data/data/com.termux/files/usr
    --libdir=/data/data/com.termux/files/usr/lib
    --sbindir=/data/data/com.termux/files/usr/bin
    --disable-rpath
    --disable-rpath-hack
    --host=aarch64-linux-android
    --disable-autodepend
    --with-dumping=none
    --with-gif=no
    --with-gnutls
    --with-jpeg=no
    --with-modules
    --with-pdumper=yes
    --with-png=no
    --with-tiff=no
    --with-xml2
    --with-xpm=no
    --with-tree-sitter
    --without-dbus
    --without-gconf
    --without-gsettings
    --without-lcms2
    --without-selinux
    --without-x
    emacs_cv_alternate_stack=yes
    emacs_cv_sanitize_address=yes
    emacs_cv_prog_cc_no_pie=no
    ac_cv_lib_elf_elf_begin=no
    gl_cv_func_dup2_works=no
    ac_cv_func_setrlimit=no
    --disable-nls
    --enable-shared
    --enable-static
    --libexecdir=/data/data/com.termux/files/usr/libexec
    'CFLAGS= -fstack-protector-strong -Oz'
    'CPPFLAGS= -isystem/data/data/com.termux/files/usr/include'
    'LDFLAGS=-L/data/data/com.termux/files/usr/lib
    -Wl,-rpath=/data/data/com.termux/files/usr/lib
    -Wl,--enable-new-dtags -Wl,--as-needed -Wl,-z,relro,-z,now'

*** native emacs

    --prefix=/home/droid
    --with-native-compilation=yes
    --with-tree-sitter

** system-configuration-features

*** termux emacs

    GMP GNUTLS LIBXML2 MODULES NOTIFY INOTIFY PDUMPER
    SECCOMP SQLITE3 THREADS TREE_SITTER XIM ZLIB

*** native emacs

    GMP GNUTLS LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER
    SECCOMP SOUND SQLITE3 THREADS TREE_SITTER ZLIB

* Performance - emacs 30.1 packaged by Termux

| test               | non-gc (s) | gc (s) | gcs | total (s) | err (s) |
|--------------------+------------+--------+-----+-----------+---------|
| bubble             |       2.05 |   0.42 |  25 |      2.46 |    0.03 |
| bubble-no-cons     |       5.19 |   0.00 |   0 |      5.19 |    0.13 |
| bytecomp           |       1.63 |   0.15 |   7 |      1.78 |    0.06 |
| dhrystone          |       3.48 |   0.00 |   0 |      3.48 |    0.07 |
| eieio              |       1.20 |   0.16 |   9 |      1.36 |    0.03 |
| fibn               |       1.30 |   0.00 |   0 |      1.30 |    0.04 |
| fibn-named-let     |       1.73 |   0.00 |   0 |      1.73 |    0.03 |
| fibn-rec           |       2.12 |   0.00 |   0 |      2.12 |    0.06 |
| fibn-tc            |       2.13 |   0.00 |   0 |      2.13 |    0.05 |
| flet               |       4.75 |   0.00 |   0 |      4.75 |    0.10 |
| font-lock          |       0.62 |   0.02 |   1 |      0.64 |    0.01 |
| inclist            |       7.00 |   0.00 |   0 |      7.00 |    0.09 |
| inclist-type-hints |       6.99 |   0.00 |   0 |      6.99 |    0.10 |
| listlen-tc         |       2.26 |   0.00 |   0 |      2.26 |    0.03 |
| map-closure        |       4.88 |   0.00 |   0 |      4.88 |    0.07 |
| nbody              |       2.91 |   0.77 |  44 |      3.68 |    0.08 |
| pack-unpack        |       0.36 |   0.04 |   2 |      0.39 |    0.01 |
| pack-unpack-old    |       0.89 |   0.07 |   4 |      0.96 |    0.02 |
| pcase              |       5.76 |   0.00 |   0 |      5.76 |    0.08 |
| pidigits           |       5.16 |   2.11 |  22 |      7.27 |    0.63 |
| scroll             |       0.56 |   0.00 |   0 |      0.56 |    0.01 |
| smie               |       1.90 |   0.04 |   2 |      1.94 |    0.03 |
|--------------------+------------+--------+-----+-----------+---------|
| total              |      64.85 |   3.77 | 116 |     68.62 |    0.69 |

* Performance - emacs 30.1 within Android Linux Terminal, with native-comp enabled

| test               | non-gc (s) | gc (s) | gcs | total (s) | err (s) |
|--------------------+------------+--------+-----+-----------+---------|
| bubble             |       0.94 |   0.06 |   1 |      1.00 |    0.45 |
| bubble-no-cons     |       0.96 |   0.00 |   0 |      0.96 |    0.01 |
| bytecomp           |       1.30 |   0.15 |   5 |      1.45 |    0.02 |
| dhrystone          |       2.14 |   0.00 |   0 |      2.14 |    0.00 |
| eieio              |       1.05 |   0.18 |   7 |      1.23 |    0.00 |
| fibn               |       0.00 |   0.00 |   0 |      0.00 |    0.00 |
| fibn-named-let     |       1.41 |   0.00 |   0 |      1.41 |    0.00 |
| fibn-rec           |       0.00 |   0.00 |   0 |      0.00 |    0.00 |
| fibn-tc            |       0.00 |   0.00 |   0 |      0.00 |    0.00 |
| flet               |       1.60 |   0.00 |   0 |      1.60 |    0.01 |
| font-lock          |       0.67 |   0.02 |   1 |      0.69 |    0.00 |
| inclist            |       1.41 |   0.00 |   0 |      1.41 |    0.00 |
| inclist-type-hints |       1.19 |   0.00 |   0 |      1.19 |    0.00 |
| listlen-tc         |       0.17 |   0.00 |   0 |      0.17 |    0.00 |
| map-closure        |       6.45 |   0.00 |   0 |      6.45 |    0.02 |
| nbody              |       1.82 |   0.15 |   1 |      1.96 |    0.59 |
| pack-unpack        |       0.36 |   0.05 |   2 |      0.41 |    0.00 |
| pack-unpack-old    |       1.10 |   0.08 |   3 |      1.18 |    0.03 |
| pcase              |       2.39 |   0.00 |   0 |      2.39 |    0.01 |
| pidigits           |       3.85 |   1.43 |  18 |      5.29 |    0.10 |
| scroll             |       0.64 |   0.00 |   0 |      0.64 |    0.00 |
| smie               |       1.56 |   0.06 |   2 |      1.62 |    0.00 |
|--------------------+------------+--------+-----+-----------+---------|
| total              |      31.04 |   2.18 |  40 |     33.22 |    0.75 |

* Results

Well that is a conclusive result: emacs running within a fully
virtualized Linux guest on the exact same hardware trounces
termux-emacs by running the benchmark suite roughly twice as fast.
I did not expect that result, but I am pleased with it!