Get a fresh set of relay/exit profiles on 0.2.5.5-alpha or later; optimize bottlenecks if found

On #7727 (moved) we had some profile results that we used to identify bottleneck functions in Tor to optimize. We should get some fresh profiles on 0.2.5.4-alpha once it's out (assuming we merge #9841 (moved)), and then see which of those bottlenecks need the most attention.

changed milestone to %Tor: 0.2.5.x-final

added 025-triaged component::core tor/tor milestone::Tor: 0.2.5.x-final performance priority::medium resolution::fixed status::closed tor-relay type::defect labels

One thought I had about that last profile, though: SHA1 was at the top of the list. OpenSSL's PRNG uses a bunch of SHA1, and is ridiculously slow for a userspace PRNG. If SHA1 turns up at the top of the list again, we should investigate whether it's our protocols' uses of SHA1, TLS's uses of SHA1, or OpenSSL's PRNG's uses of SHA1 that are most to blame.

Trac:
Keywords: tor-relay performance deleted, tor-relay performance 025-triaged added

(to clarify: we should optimize any enormous bottlenecks in 0.2.5, and save medium to small bottlenecks for 0.2.6)

Here are the maximally simple instructions as I understand them.

• Run Linux. Install perf. (On Debian, this is 'apt-get install linux-tools')
• (For call graphs only) Build Tor with -fno-omit-frame-pointer
• Start a Tor server with DisableDebuggerAttachment 0 set
• Wait for the server to get load
• Find the PID of the Tor process; call it PID.
• Run "perf record -p $PID"
  • (To benchmark worker threads too) It might be a good idea to do "perf record -a -p $PID"
  • (For call graphs only) Instead you might need something like "perf record --call-graph fp -a -g -p $PID"
• After a while (an hour or so?), ctrl-C the 'perf record' command. It will have written its results into perf.data.
• Run "perf report --stdio > results". Gzip that file and send it to nick.
  • (For call graphs only) You might need "perf report --call-graph -G --stdio > results".

These instructions probably suck! Please help me improve them.

Would love to give it a try. Can you clarify specific commands to build Tor? Is it

./configure -fno-omit-frame-pointer; make && make install ?

For the debian package it would probably be like so:

• cd /usr/src
• apt-get source tor
• cd tor-0.2.5*
• vim debian/rules
• append "CFLAGS=-fno-omit-frame-pointer"
• dpkg-buildpackage -B

Packages would then lie in /usr/src.

(Updated, according to #6 (closed))

cd tor-0.2.4*

Remember, I need profiles from Tor 0.2.5, not Tor 0.2.4.

Yes, I am running tor-0.2.5.2-alpha on Centos. It is not a 50+ Mbps relay, but I will give it shot to compile some data for you.

What I most need is information about 0.2.5.4-alpha or later. 0.2.5.4-alpha has some performance improvements that should (I hope) affect the numbers a lot.

[But information about 0.2.5.2-alpha is still useful, because (a) it will let us know what stuff looked like before 0.2.5.4-alpha, and (b) it will help us figure out what the instructions for running perf should say.]

I can download and build 0.2.5.4-alpha. I build Tor from source anyway.

I will try to run it on 0.2.5.2 first, then build 0.2.5.4 and run it again.

Trac:
tor-0.2.5.2-alpha-results.gz

Tor-0.2.5.2-alpha

Trac:
Username: esbek

tor-0.2.5.4-alpha-ESBEK-tor5-28.05.2014-20.30.43.gz

Trac:
Username: esbek

Hm.

    28.21%      tor  libcrypto.so.1.0.0     [.] 0x000000000007398c                           
    14.41%      tor  tor                    [.] 0x00000000000f0991                           

Was this version of Tor built without debugging symbols or something?

Replying to nickm: ...

Was this version of Tor built without debugging symbols or something? It was built with this settings: ./configure --prefix=/usr --build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu --mandir=/usr/share/man --infodir=/usr/share/info --datadir=/usr/share --sysconfdir=/etc --localstatedir=/var/lib --libdir=/usr/lib64 --disable-silent-rules --disable-dependency-tracking --disable-buf-freelists --enable-asciidoc --docdir=/usr/share/doc/tor-0.2.5.4_alpha-r1 --enable-instrument-downloads --disable-bufferevents --enable-curve25519 --disable-nat-pmp --enable-gcc-hardening --enable-linker-hardening --disable-transparent --enable-threads --disable-upnp --disable-tor2web-mode --disable-unittests --disable-coverage

Trac:
Username: esbek

I forgot that I stripped symbols. So it will take some time ...

Trac:
Username: esbek

Trac:
Username: esbek

tor-0.2.5.4-alpha-ESBEK-tor5-29.05.2014-00.32.10.gz

Trac:
Username: esbek