Arch programs from repos and multithread support

Mr. Alex · 2010-12-20 15:04:15

Support of how many CPU cores/threads maintainers compile programs with? Programs which are available from Arch repositories.

skunktrader · 2010-12-20 15:18:42

As far as I know the kernel is compiled with a maximum of 16 cores

graysky · 2010-12-20 15:20:47

The programs don't have specific support AFAIK. The kernels do...

x86_64 = 64
i686 = 8

Last edited by graysky (2010-12-20 15:21:52)

karol · 2010-12-20 15:20:56

https://bugs.archlinux.org/task/21352

Thomas Bächler (brain0) wrote:

The settings have been changed to:
i686: 8 cores (maximum)
x86_64: 64 cores

Last edited by karol (2010-12-20 15:22:20)

Mr.Elendig · 2010-12-20 15:36:59

Mr. Alex wrote:

Support of how many CPU cores/threads maintainers compile programs with? Programs which are available from Arch repositories.

This is up to the application themself. Most apps are not written with SMP support.

karol · 2010-12-20 15:49:48

Mr.Elendig wrote:

Mr. Alex wrote:
Support of how many CPU cores/threads maintainers compile programs with? Programs which are available from Arch repositories.
This is up to the application themself. Most apps are not written with SMP support.

I know you asked for apps from the repos, but some from the AUR are multithreaded:
http://aur.archlinux.org/packages.php?ID=28623
http://aur.archlinux.org/packages.php?ID=23958
so use those if you need.

Mr. Alex · 2010-12-20 16:09:48

graysky wrote:

The programs don't have specific support AFAIK

https://wiki.archlinux.org/index.php/Makepkg
The MAKEFLAGS option can be used to specify additional options for make. Users with multi-core/multi-processor systems can specify the number of jobs to run simultaneously. Generally -j2, plus 1 for each additional core/processor is an adequate choice. Optimizing for multiple cores can sometimes increase compiling performance, shortening compile times. However, be warned that occasionally using anything but the default can cause compilation problems, though many have agreed that -j3 is fairly safe to use for the majority of packages.

Last edited by Mr. Alex (2010-12-20 16:10:26)

Mr.Elendig · 2010-12-20 16:14:36

Mr. Alex wrote:

graysky wrote:
The programs don't have specific support AFAIK
https://wiki.archlinux.org/index.php/Makepkg
The MAKEFLAGS option can be used to specify additional options for make. Users with multi-core/multi-processor systems can specify the number of jobs to run simultaneously. Generally -j2, plus 1 for each additional core/processor is an adequate choice. Optimizing for multiple cores can sometimes increase compiling performance, shortening compile times. However, be warned that occasionally using anything but the default can cause compilation problems, though many have agreed that -j3 is fairly safe to use for the majority of packages.

This only affects how many threads that make will spawn. It's compile time only and won't change the behaviour of the resulting binary one bit.

A single threaded app will always be single threaded, even if your compile forked off 30 threads when it compiled it.

Last edited by Mr.Elendig (2010-12-20 16:16:00)

karol · 2010-12-20 16:16:01

Mr. Alex wrote:

graysky wrote:
The programs don't have specific support AFAIK
https://wiki.archlinux.org/index.php/Makepkg
The MAKEFLAGS option can be used to specify additional options for make. Users with multi-core/multi-processor systems can specify the number of jobs to run simultaneously. Generally -j2, plus 1 for each additional core/processor is an adequate choice. Optimizing for multiple cores can sometimes increase compiling performance, shortening compile times. However, be warned that occasionally using anything but the default can cause compilation problems, though many have agreed that -j3 is fairly safe to use for the majority of packages.

'-j24' means you will compile the app using 24 threads but it may still be singlethreaded. One thing has nothing to do with the other.

graysky · 2010-12-20 16:20:53

karol wrote:

'-j24' means you will compile the app using 24 threads but it may still be singlethreaded. One thing has nothing to do with the other.

Right! Again, if the code itself supports multi-threads, and has been compiled with this support, it will use them if the kernel and your hardware supports them. To echo what others have said, the make flags have nothing to do with the compiled app.

Mr. Alex · 2010-12-20 16:40:26

Thanks for explaination.

karol · 2010-12-20 19:21:44

I've found one package that is explicitly multithreaded: http://www.archlinux.org/packages/extra/i686/ypbind-mt/

Mr. Alex · 2010-12-27 06:22:35

How many cores/CPUs does program for compiling from AUR support (I guess it's makepkg)?

Allan · 2010-12-27 06:25:33

Read about MAKEFLAGS and look in makepkg.conf.

Mr. Alex · 2010-12-27 07:23:55

I have a 2-core CPU and configured multicore support as "-j3". It compiles like

graysky · 2010-12-27 14:29:03

@mra - try compiling something like a kernel and you'll see a more heavy usage. Although not a compiling question, try doing some x264 encoding and you'll also see your processors pegged.

That is w/ -j4 on a quad core chip (not -j5 when using the bfs!)

Last edited by graysky (2010-12-27 14:30:46)

Arch Linux

#1 2010-12-20 15:04:15

Arch programs from repos and multithread support

#2 2010-12-20 15:18:42

Re: Arch programs from repos and multithread support

#3 2010-12-20 15:20:47

Re: Arch programs from repos and multithread support

#4 2010-12-20 15:20:56

Re: Arch programs from repos and multithread support

#5 2010-12-20 15:36:59

Re: Arch programs from repos and multithread support

#6 2010-12-20 15:49:48

Re: Arch programs from repos and multithread support

#7 2010-12-20 16:09:48

Re: Arch programs from repos and multithread support

#8 2010-12-20 16:14:36

Re: Arch programs from repos and multithread support

#9 2010-12-20 16:16:01

Re: Arch programs from repos and multithread support

#10 2010-12-20 16:20:53

Re: Arch programs from repos and multithread support

#11 2010-12-20 16:40:26

Re: Arch programs from repos and multithread support

#12 2010-12-20 19:21:44

Re: Arch programs from repos and multithread support

#13 2010-12-27 06:22:35

Re: Arch programs from repos and multithread support

#14 2010-12-27 06:25:33

Re: Arch programs from repos and multithread support

#15 2010-12-27 07:23:55

Re: Arch programs from repos and multithread support

#16 2010-12-27 14:29:03

Re: Arch programs from repos and multithread support

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