On 6 October 2011 07:46, Stefan Behnel <[email protected]> wrote: > mark florisson, 05.10.2011 15:53: >> >> On 5 October 2011 08:16, Stefan Behnel wrote: >>> >>> mark florisson, 04.10.2011 23:19: >>>> >>>> Another issue is that Cython compile time is increasing with the >>>> addition of control flow and cython utilities. If you use fused types >>>> you're also going to combinatorially add more compile time. >>> >>> I don't see that locally - a compiled Cython is hugely fast for me. In >>> comparison, the C compiler literally takes ages to compile the result. An >>> external shared library may or may not help with both - in particular, it >>> is >>> not clear to me what makes the C compiler slow. If the compile time is >>> dominated by the number of inlined functions (which is not unlikely), a >>> shared library + header file will not make a difference. >> >> Have you tried with the memoryviews merged? > > No. I didn't expect the difference to be quite that large. > > >> e.g. if I have this code: >> >> from libc.stdlib cimport malloc >> cdef int[:] slice =<int[:10]> <int *> malloc(sizeof(int) * 10) >> >> [0] [14:45] ~ ➤ time cython test.pyx >> cython test.pyx 2.61s user 0.08s system 99% cpu 2.695 total >> [0] [14:45] ~ ➤ time zsh compile >> zsh compile 1.88s user 0.06s system 99% cpu 1.946 total >> >> where 'compile' is the script that invoked the same gcc command >> distutils uses. As you can see it took more than 2.5 seconds to >> compile this code (simply because the memoryview utilities get >> included). > > Ok, that hints at serious performance problems. Could you profile it to see > where the issues are? Is it more that the code is loaded from an external > file? Or the fact that more utility code is parsed than necessary?
I haven't profiled it yet (I'll do that), but I'm fairly sure it's the parsing of Cython utility files (not the loading). Maybe Tempita also adds to the overhead, I'll find out. > It's certainly not obvious why the inclusion of static code, even from an > external file, should make any difference. > > That being said, it's not we were lacking the infrastructure for making > Python code run faster ... > Heh, indeed. In this case I think caching will solve all our problems. >>>> I'm sure >>>> this came up earlier, but I really think we should have a libcython >>>> and a cython.h. libcython (a shared library) should contain any common >>>> Cython-specific code not meant to be inlined, and cython.h any types, >>>> macros and inline functions etc. >>> >>> This has a couple of implications though. In order to support this on the >>> user side, we have to build one shared library per installed package in >>> order to avoid any Cython versioning issues. Just installing a versioned >>> "libcython_x.y.z.so" globally isn't enough, especially during >>> development, >>> but also at deployment time. Different packages may use different CFLAGS >>> or >>> Cython options, which may have an impact on the result. Encoding all >>> possible factors in the file name will be cumbersome and may mean that we >>> still end up with a number of installed Cython libraries that correlates >>> with the number of installed Cython based packages. >> >> Hm, I think the CFLAGS are important so long as they are compatible >> with Python. When the user compiles a Cython extension module with >> extra CFLAGS, this doesn't affect libpython. Similarly, the Cython >> utilities are really not the user's responsibility, so libcython >> doesn't need to be compiled with the same flags as the extension >> module. If still wanted, the user could either recompile python with >> different CFLAGS (which means libcython will get those as well), or >> not use libcython at all. CFLAGS should really only pertain to user >> code, not to the Cython library, which the user shouldn't be concerned >> about. > > Well, it's either the user or the OS distribution that installs (and > potentially builds) the libraries. That already makes it two responsible > entities for many systems that have to agree on what gets installed in what > way. I'm just saying, don't underestimate the details in world wide > deployments. > > Stefan > _______________________________________________ > cython-devel mailing list > [email protected] > http://mail.python.org/mailman/listinfo/cython-devel > _______________________________________________ cython-devel mailing list [email protected] http://mail.python.org/mailman/listinfo/cython-devel
