[Linux] Is LUAJIT really working?

[JDCodeIt]

I have compiled with flag ENABLE_LUAJIT, but I don't see outstanding LUA performance improvement in the server.

Linux's ldd reports that the LUAJIT library is unused - any idea why? The lua wrapper code is definitely being compiled.

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ldd -u bin/minetestserver
Unused direct dependencies:
   /lib/i386-linux-gnu/libz.so.1
   /usr/lib/i386-linux-gnu/libsqlite3.so.0
   /usr/lib/i386-linux-gnu/libluajit-5.1.so.2
   /lib/i386-linux-gnu/librt.so.1
   /lib/i386-linux-gnu/libpthread.so.0
   /lib/i386-linux-gnu/libncurses.so.5
   /usr/lib/libpq.so.5
   /usr/lib/i386-linux-gnu/libleveldb.so.1
   /usr/lib/i386-linux-gnu/libhiredis.so.0.10
   /usr/lib/i386-linux-gnu/libcurl.so.4
   /lib/i386-linux-gnu/libm.so.6
   /lib/i386-linux-gnu/libgcc_s.so.1


[rubenwardy]

Have you installed the luajit dev libraries?
Does the output of cmake mention "luajit found"

[JDCodeIt]

Yes, installed the dev libraries

The first output of cmake shows it finds the library:

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cmake . -DBUILD_SERVER=TRUE
-- *** Will build version 0.4.14-dev ***
-- Found Irrlicht: /usr/lib/i386-linux-gnu/libIrrlicht.so 
-- Found CURL: /usr/lib/i386-linux-gnu/libcurl.so 
-- cURL support enabled.
-- GetText disabled.
-- Found OpenAL: /usr/lib/i386-linux-gnu/libopenal.so 
-- Found VORBIS: /usr/include 
-- Sound enabled.
-- checking for module 'freetype2'
--   found freetype2, version 17.1.11
-- Found Freetype: /usr/lib/i386-linux-gnu/libfreetype.so (found version "17.1.11")
-- Freetype enabled.
-- Found LuaJit: /usr/lib/i386-linux-gnu/libluajit-5.1.so

[ExeterDad]

I just now built 0.4.14 (server) and it linked to my libs just fine

+ Spoiler

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leeh@acer ~ $ ldd /usr/bin/minetestserver
   linux-vdso.so.1 (0x00007fff86f89000)
   libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007ff30d1f0000)
   libsqlite3.so.0 => /usr/lib/x86_64-linux-gnu/libsqlite3.so.0 (0x00007ff30cf27000)
   libjsoncpp.so.0 => /usr/lib/libjsoncpp.so.0 (0x00007ff30cce1000)
   libluajit-5.1.so.2 => /usr/lib/x86_64-linux-gnu/libluajit-5.1.so.2 (0x00007ff30ca73000)
   libgmp.so.10 => /usr/lib/x86_64-linux-gnu/libgmp.so.10 (0x00007ff30c7f0000)
   librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007ff30c5e7000)
   libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007ff30c3ca000)
   libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007ff30c1c6000)
   libncurses.so.5 => /lib/x86_64-linux-gnu/libncurses.so.5 (0x00007ff30bfa0000)
   libtinfo.so.5 => /lib/x86_64-linux-gnu/libtinfo.so.5 (0x00007ff30bd76000)
   libform.so.5 => /usr/lib/x86_64-linux-gnu/libform.so.5 (0x00007ff30bb66000)
   libspatialindex.so.3 => /usr/lib/x86_64-linux-gnu/libspatialindex.so.3 (0x00007ff30b8a2000)
   libcurl-gnutls.so.4 => /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4 (0x00007ff30b635000)
   libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007ff30b32a000)
   libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007ff30b028000)
   libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007ff30ae12000)
   libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007ff30aa67000)
   /lib64/ld-linux-x86-64.so.2 (0x00007ff30d42b000)
   libidn.so.11 => /usr/lib/x86_64-linux-gnu/libidn.so.11 (0x00007ff30a832000)
   librtmp.so.1 => /usr/lib/x86_64-linux-gnu/librtmp.so.1 (0x00007ff30a615000)
   libssh2.so.1 => /usr/lib/x86_64-linux-gnu/libssh2.so.1 (0x00007ff30a3eb000)
   libnettle.so.4 => /usr/lib/x86_64-linux-gnu/libnettle.so.4 (0x00007ff30a1b9000)
   libgnutls-deb0.so.28 => /usr/lib/x86_64-linux-gnu/libgnutls-deb0.so.28 (0x00007ff309e9a000)
   libgssapi_krb5.so.2 => /usr/lib/x86_64-linux-gnu/libgssapi_krb5.so.2 (0x00007ff309c4e000)
   libkrb5.so.3 => /usr/lib/x86_64-linux-gnu/libkrb5.so.3 (0x00007ff30997a000)
   libk5crypto.so.3 => /usr/lib/x86_64-linux-gnu/libk5crypto.so.3 (0x00007ff309749000)
   libcom_err.so.2 => /lib/x86_64-linux-gnu/libcom_err.so.2 (0x00007ff309544000)
   liblber-2.4.so.2 => /usr/lib/x86_64-linux-gnu/liblber-2.4.so.2 (0x00007ff309335000)
   libldap_r-2.4.so.2 => /usr/lib/x86_64-linux-gnu/libldap_r-2.4.so.2 (0x00007ff3090e3000)
   libhogweed.so.2 => /usr/lib/x86_64-linux-gnu/libhogweed.so.2 (0x00007ff308eb3000)
   libgcrypt.so.20 => /lib/x86_64-linux-gnu/libgcrypt.so.20 (0x00007ff308bd1000)
   libp11-kit.so.0 => /usr/lib/x86_64-linux-gnu/libp11-kit.so.0 (0x00007ff30898a000)
   libtasn1.so.6 => /usr/lib/x86_64-linux-gnu/libtasn1.so.6 (0x00007ff308776000)
   libkrb5support.so.0 => /usr/lib/x86_64-linux-gnu/libkrb5support.so.0 (0x00007ff30856a000)
   libkeyutils.so.1 => /lib/x86_64-linux-gnu/libkeyutils.so.1 (0x00007ff308365000)
   libresolv.so.2 => /lib/x86_64-linux-gnu/libresolv.so.2 (0x00007ff30814e000)
   libsasl2.so.2 => /usr/lib/x86_64-linux-gnu/libsasl2.so.2 (0x00007ff307f31000)
   libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007ff307d1f000)
   libffi.so.6 => /usr/lib/x86_64-linux-gnu/libffi.so.6 (0x00007ff307b17000)


Edit: Just did a pull from dev and it linked as well.
Is it possible you have the headers installed, but the libs are missing? Can you confirm libluajit-5.1.so is in your libs dir? Weird.

[sfan5]

With the ldd output you quoted your minetestserver would be completely non-functional.

libz.so is required for compressing MapBlocks when saving them to disk, libsqlite3.so is the default backend for saving MapBlocks and can't be disabled, libpthread.so is required for threading which is used by the minetest server and can't be removed either.

In short: Don't believe the ldd output and look at what CMake's saying.

[kaeza]

To see if you're running LuaJIT, create a dummy mod with this code:

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assert(jit)


If you're running under plain Lua, you'll get an "assertion failed!" error message.

[JDCodeIt]

Well I guess it is working.. I bracketed with log messages, and this was the output on the terminal.

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Code: Select all

2016-06-08 13:35:21: ACTION[Main]: assert(jit)
2016-06-08 13:35:21: ACTION[Main]: done with assert(jit)


Hard to imagine the lua performance without jit - really, 30 times slower? With reasonably setup technic and pipeworks systems, I regularly get the warning that ABM's are taking too long - like 600+ms (Xubuntu AMD A6-5200 quad-core @ 2.0 GHz, 8 GB RAM)