Talk:Distcc

DistCC Needs a Tuning Section
If I'm not mistaken, DistCC pretty much ignores the "/etc/make.conf" or "/etc/portage/make.conf" MAKEOPTS variable, and spawns the jobs as needed until the jobs fallback to the local box (not via network) for compiling. (So tinkering with the MAKEOPTS variable is likely not needed, as this variable is usually already setup on most Gentoo boxes.)

Think I figured how to properly tune DistCC. Add the following "--jobs" option to the server or helper box performing the compiling. Typically the "--jobs" option will mirror the MAKEOPTS variable within the "/etc/portage/make.conf" file or CPU's+1. Notice that the DistCC server (or helper box) now has spawned ten distccd threads. (ie. ps ax |grep distccd)

/etc/conf.d/distccd: DISTCCD_OPTS="--port 3632 --log-level warning --log-file /var/log/distccd.log -N 15 --allow 127.0.0.1 --allow 192.168.1.0/24 --jobs 10"

On the client box, the "/etc/distcc/hosts" for designating the DistCC server (or helper box); the jobs can be limited, but not designated more jobs? /etc/distcc/hosts 192.168.1.5/5

Per DistCC manual; by defaults, DistCC spawns four threads or four jobs (plus one) for per each host listed within the /etc/distcc/hosts file.

I'm still slightly confused here. And likely the "--jobs 10" option needs to be integrated into both the client and server/helper boxes. And then the /etc/distcc/hosts limits the job number as necessary by using the /num suffix option to the server address?

--Roger (talk) 22:26, 1 May 2014 (UTC)

DistCC Pump Mode
Article jumps right into pump mode. Might be nice to have a very very brief one sentence explaining pump mode. ie. "Distcc's pump mode accelerates remote compilation with distcc by also distributing preprocessing to the servers. (ie. man pump)" --Roger (talk) 19:05, 21 January 2015 (UTC)


 * I missed to read the discussions page before changing the article and added quick note about pump mode in the configuration section. --Totktonada (talk) 03:24, 19 February 2016 (UTC)

The only other noteworthy item within the pump manual is; "Note that distcc's pump-mode assumes that sources files will not be modified during the lifetime of the include server, so modifying source files during a build may cause inconsistent results." Of which, I don't think I've ever personally seen source files modified during compilation, unless somebody remotely logged into a version control system while the sources were being recompiled. Being a source Linux based distribution, I still don't think the later is worth much concern? --Roger (talk) 18:15, 21 January 2015 (UTC)


 * As I understand it’s about situations when some different macros defined before including a header in different compilation units. Or distcc able to check such things and it’s out of topic? Maybe your understanding right. Anyway I think it’s unlikely to be common and concerned user surely looks into man page, briefly at least. The article I guess shouldn’t describe all kind of uncommon weird things that may lead to breaking build process or broken executable. --Totktonada (talk) 03:24, 19 February 2016 (UTC)

Also, no mention of requiring to add ",cpp,lzo" (ie. 192.168.1.2/10,cpp,lzo) to the hosts lines within the /etc/distcc/hosts file! This is a requisite for DistCC pump mode! The example 192.168.1.2/10,cpp,lzo first specifies a remote compiler host, then limit sending 10 jobs max to the remote host compiler, including sending cpp jobs with lzo compression for which the later two cpp/lzo options are required for pump mode to work. Else, the user will see warnings and errors upon pump emerge! --Roger (talk) 19:05, 21 January 2015 (UTC)


 * Thanks! I’m going to try pump mode on the week and will return with some thought here. --Totktonada (talk) 03:24, 19 February 2016 (UTC)


 * You right. I updated the article: expanded configuration section and usage example. --Totktonada (talk) 01:03, 24 February 2016 (UTC)

Command for obtaining -march=native options
Previously, this command was listed as the mechanism for obtaining the CFLAGS equivent to -march=native:

However, it has some flaws. Something valuable that the -march=native option obtains is information about the processor's cache (including the L1 line size). However, the one-liner I've replaced it with I can't promise will be 100% accurate on all archs, since I'm filtering out the hordes of -mno-* flags that gcc puts in there since 4.7 or so. I'm betting on gcc using these flags to add features to a base march, but if it uses a -mno-* flag to remove a feature from any arch, then this will be broken.

Maybe what we really need is a mechanism for the distcc client to insert these flags and relieve the user from having to fish them out.

Daniel Santos (talk) 22:42, 26 January 2015 (UTC)


 * I don’t understand why concerned about 'all archs'? C[XX]FLAGS should fit particular machine and be equivalent to '-march=native' on *that* machine (with some additions/modifications/optimization flags according to you). There is a good article about filtering redundant flags from gcc’s output—'Inlining -march=native for distcc'—it’s mentioned in the configuration section and can be found in 'External resources' too. But maybe scripting around gcc’s output is good idea. --Totktonada (talk) 03:41, 19 February 2016 (UTC)

No Real Mention of DistCC Required Packages with Versions Synced
I always thought there were a few packages with versions requiring to be synchronized across servers and clients for DistCC to work flawlessly. The packages I thought requiring versions to be synchronized across servers and clients were: distcc, glibc, gcc, binutils, ... ? Or is the only package requiring to have a similar major version is GCC? No mention or strong noting or warning for this version synchronization seems to be currently mentioned within the WIKI page. There were strong warnings in the past elsewhere for such package version synchronization, else users would risk major system breaks. I should also mention, the previous fore mentioned built with similar USE flags (ie. configure --help) as well? --Roger (talk) 11:00, 4 October 2015 (UTC)

Testing
When testing main.o with command './main.o' I get message:

-bash: ./main.o: Permission denied

After I chmod main.o with command 'chmod +x main.o' I get message:

-bash: ./main.o: cannot execute binary file: Exec format error

I need an explanation why can't I run main.o?

--Best, Pál (talk) 07:00, 6 February 2016 (UTC)


 * The example was particuary broken. It missed linking and suggested to run an object file instead of an executable. Now it should be fine. --Totktonada (talk) 04:06, 19 February 2016 (UTC)

Another SSH usage example
Suppose you are on a powerful system (system A) and you want to help a tiny device to cross-compile (system B). You can connect from A to B with ssh.

On the system A

 * install the distcc server
 * configure it to allow connections only from localhost :


 * run the distcc server

On the system B
distcc-config --set-hosts "127.0.0.1/16 localhost/2"
 * install distcc
 * set participating hosts, here 16 jobs for the helper, 2 jobs for locale cores :

From the system A

 * Open a reversed SSH tunnel to the system B :

You can now update your tiny system, jobs will be sent to the distcc server through the reversed SSH tunnel.