On Wednesday, November 13, 2024 at 11:06:46 PM UTC+9 Michael Orlitzky wrote:
On 2024-11-13 01:12:25, Kwankyu Lee wrote: > Hi, > > According to our installation guide: > > *One useful setting for this variable when building Sage is MAKE='make > -jNUM' to tell the make program to run NUM jobs in parallel when building. > Note that some Sage packages may not support this variable.* > > and our main build scripts are sprinkled with $(MAKE) instead of invoking > "make" directly. > > But as I understand the jobserver > (https://www.gnu.org/software/make/manual/html_node/Job-Slots.html), only > the top-level make command should get "-jNUM" flag and sub make commands > should not get "-jNUM flag, for the jobserver to work across all make > commands. > > Hence we should revise the paragraph in the installation guide to not > recommend to define *MAKE='make -jNUM', but to build sage by make -jNUM at > the top-level.* > > *Am I right?* Sub-invocations of $(MAKE) within a Makefile coordinate the number of jobs by passing information around through the MAKEFLAGS variable. So inside Sage's own Makefiles, either should work. I think where the difference becomes important is in the sage-the-distro packages, under build/pkgs. These are built with scripts that run $MAKE, but not as part of another Makefile -- so I doubt that the jobserver/number-of-jobs information gets relayed unless you put it in the $MAKE variable yourself. (But if you are thinking that this would ultimately start too many jobs, you are probably right.) Right. I think package build scripts should relay the MAKEFLAGS variable so that the jobserver initiated by the top-level make run by a user controls the number of jobs across the whole build process. Defining MAKE='make -jNUM' disables the jobserver, and hence seems to be a bad practice. > Moreover I think SAGE_NUM_THREADS environment variable should be used if a > sage package wants to run parallel jobs, instead of relying on *MAKE='make > -jNUM'.* The doctest runner is capable of coordinating with the GNU Make jobserver so that, for example, "make -j4 test" will start the correct number of parallel test threads. This is akin to how "make -j4 test" works in a typical autotools package; it will run up to four tests at the same time. In short it is a way to pass sage-the-distro information down to sage-the-library. OK. Otherwise, users who are familiar with "make -j" would also need to know about the sage-only SAGE_NUM_THREADS variable, and set it redundantly. If defined, SAGE_NUM_THREADS may be used to overrule the jobserver. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/sage-devel/8636fac4-5797-458f-9cbd-f005daa8ececn%40googlegroups.com.
