13:14 <mdiers_> simberg: yt?

13:16 <mdiers_> simbergm: yt?

19:38 <gonidelis> hello! i am trying to install HPX on my ubuntu16 machine and i have encountered a problem with hwloc on my installation

19:39 <zao> How fun! What happens?

19:41 <gonidelis> i am installing hwloc using `sudo apt install hwloc` but after trying `cmake -DHPX_WITH_MALLOC=system` my cmake pops "Hwloc could not be found..."

19:41 <zao> Do you have libhwloc-dev?

19:41 <zao> Packages on Ubuntu are often split into a executable/runtime-library package and a matching development package with headers/etc.

19:42 <gonidelis> Oh no! Let me try it. Thanks a lot for your response. Yeah I get it...

19:43 <gonidelis> Well thanks a lot! It worked. WOW! Thank you...

19:44 <zao> Yay!

20:21 <gonidelis> well then I try `make all` and I get "CMakeFiles/Makefile2:46816: recipe for target 'libs/threadmanager/CMakeFiles/hpx_threadmanager.dir/all' failed". Do you know what may be the cause?

20:23 <zao> The cause may be further up in your output.

20:23 <zao> Not off-hand, but it was long since I last built HPX.

20:25 <gonidelis> you are right. it actually must be : * error: call of overloaded ‘get()’ is ambiguous*

20:42 <gonidelis> are `tcmalloc` or/and `jemalloc` mandatory in order for `make install` to succeed?

20:43 <zao> I'd expect `system` allocator to be sufficient.

20:56 <simbergm> gonidelis: what compiler are you using? I suspect you need a newer gcc...

20:58 <gonidelis> `gcc --version` outputs: *5.4.0*

20:58 <zao> simbergm: Documentation still documents 4.9 or something.

20:58 <simbergm> grr, we need to update the documentation in that case...

20:58 <zao> https://stellar-group.github.io/hpx/docs/sphinx/latest/html/manual/building_hpx.html#software-and-libraries

20:59 <simbergm> yeah, that's a mistake

20:59 <gonidelis> What gcc version is needed though?

20:59 <simbergm> gonidelis: are you building 1.4.0 or master?

20:59 <simbergm> for master you probably need 7 or higher

20:59 <simbergm> and if you're really on ubuntu 16.04 I recommend you upgrade...

21:00 <zao> simbergm: Hey, my cluster is still 16.04.

21:01 <simbergm> 1.4.0/1 should still work with gcc 5

21:01 <simbergm> heh, whatever works for you

21:01 <gonidelis> yeah I am building master. Should I upgrade my gcc I 'll try again and I will inform you on my progress. Thanks a lot.

21:02 <simbergm> yep, in that case gcc 7 or higher, or clang 4 or higher (if I remember correctly)

21:02 <gonidelis> Well I recently reinstalled Ubuntu16. The reason I picked this distro is because there are plenty fixes on the internet as it is older than 18. Do you think I should upgrade in order to contribute to HPX?

21:07 <zao> gonidelis: On cluster systems an older OS tends to be "fine" as long as one can provide decent compilers and libraries in a module system on top, as long as drivers and kernel bugs aren't too intrusive.

21:08 <zao> On a workstation, 18.04 is a fine version to be on, somewhat newer versions in the OS itself, desktop environments tend to work better.

21:09 <zao> gonidelis: I'm guessing you intend to apply for GSoC, maybe?

21:09 <gonidelis> well, yes I do...

21:17 <zao> (I'm not, if you're scared of competition :D)

21:17 <zao> You can probably develop on anything, but something that's comfortably above minspec is probably helpful.

21:20 <gonidelis> Well I am installing Ubuntu18 right now as installing gcc-7 didn't help (as expected)

21:24 <zao> Did you specify that it should use the compiler (with `-DCMAKE_C_COMPILER=gcc-7 -DCMAKE_CXX_COMPILER=g++-7` or suchlike)?

21:27 <gonidelis> wasn't aware of this particular directive. my bad.

21:29 <zao> As the distro and all libs are built with one particular compiler, additional compiler packages tend to have alternate names, so that when something uses "gcc" or "g++", they get the normal one and you get to specify explicitly if you need to use a different one.

21:39 <gonidelis> yeah I absolutely get it. Thank you. Actually I am waiting for `make` to complete right now. I wanted to ask something though: you previously said that your cluster runs Ubuntu16 and you mentioned 'workstation' as an alternative. As I am a newcomer and I certainly hope to stay (I love c++ and parallelization/distributes systems is my passion) could

21:39 <gonidelis> you tell me whether any particular hardware is needed in order to contribute to HPX (not just for GSoC)?

21:40 <zao> Most of it is just regular PC development.

21:41 <gonidelis> I have been developing all my code/projects so far on a ThinkPad T430 with an i5-3320 quad core and 8gb ram. Oh I see... So it must be performance tests that you run on clusters right? I mean in order to achieve computational improvement...

21:42 <zao> The TCP parcelport might need some networking, the infiniband parcelport would need infiniband connectivity, there's some side projects that use GPUs.

21:43 <zao> The schedulers might have fun corner cases if you have a more complicated machine layout.

21:43 <zao> Depends a bit on what project you intend to propose.

21:44 <zao> If you're going to build tests/examples on that 8GB machine, you can probably not build with high -j parallelism, as linking them takes a lot of RAM.

21:44 <zao> "my" cluster would be a bit of a misnomer by the way, as it's the one I use at work.

21:46 <zao> The HPX group has access to resources too, but it tends to help if you can do some local development.

21:47 <gonidelis> ok I 'll definately take my hardware into account as far as project selection is concerned. What about contribution in general? Could I become an HPX developer with that kind of hardware?

21:48 <gonidelis> Yeah. I imagined that you will have access as a team on certain resources (that was my next question actually ;p ). that might answer my first one too...

21:49 <zao> I forget how it has gone the previous years, but I'd expect that accepted students would have access to the smaller resources by need (which still has a few nodes in a batch system).

21:51 <zao> A full build of HPX with tests and examples tends to take a lot of time, but actively developing and building parts of it tends to be fine on most setups.

21:58 <zao> I've built HPX a whole bunch of times on my old work macbook, which was along those specs.

22:06 <gonidelis> perfect! I ll try to get familiarized with HPX then, trying to implement some tests / test-code as soon as possible and I will soon provide you with a proposal. Thanks for your help/info!