On Tue, Sep 25, 2012 at 08:55:23AM +0700, Nguyen Thai Ngoc Duy wrote:
> On Tue, Sep 25, 2012 at 7:25 AM, Jeff King <peff@xxxxxxxx> wrote:
> > +ifdef USE_LUA
> > + BASIC_CFLAGS += -DUSE_LUA `pkg-config --cflags lua5.2`
> > + EXTLIBS += `pkg-config --libs lua5.2`
> > +endif
> > +
>
> I remember we paid noticeable penalty when linking with libcurl to
> main git binary and Linus removed libcurl from main git, moving it to
> git-http-*. Do we pay similar penalty linking to liblua?
I don't think so. The real problem with libcurl is that it brings in a
ton of other libraries:
$ ldd /usr/lib/x86_64-linux-gnu/libcurl.so | awk '{print $1}'
linux-vdso.so.1
libidn.so.11
libssh2.so.1
liblber-2.4.so.2
libldap_r-2.4.so.2
librt.so.1
libgssapi_krb5.so.2
libssl.so.1.0.0
libcrypto.so.1.0.0
librtmp.so.0
libz.so.1
libc.so.6
libgcrypt.so.11
libresolv.so.2
libsasl2.so.2
libgnutls.so.26
libpthread.so.0
/lib64/ld-linux-x86-64.so.2
libkrb5.so.3
libk5crypto.so.3
libcom_err.so.2
libkrb5support.so.0
libdl.so.2
libkeyutils.so.1
libgpg-error.so.0
libtasn1.so.3
libp11-kit.so.0
Compare with lua:
$ ldd /usr/lib/x86_64-linux-gnu/liblua5.2.so | awk '{print $1}'
linux-vdso.so.1
libm.so.6
libdl.so.2
libc.so.6
/lib64/ld-linux-x86-64.so.2
The original timings from Linus are here:
http://article.gmane.org/gmane.comp.version-control.git/123946
The main issue is really hitting all those libraries on a cold cache.
Here are before-and-after timings of:
echo 3 >/proc/sys/vm/drop_caches && git
which should basically just measure startup time. All times are
best-of-five.
[before]
real 0m0.065s
user 0m0.000s
sys 0m0.004s
[after]
real 0m0.063s
user 0m0.000s
sys 0m0.004s
So we actually did better, though the difference is well within the
run-to-run noise. I don't think it's a big deal.
-Peff
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