I made both issues into trac tickets. See #269 and #270. One is a blocker for MPIR 1.3 as it regards a serious bug by the looks of it.
Bill. 2010/1/3 Cactus <rieman...@googlemail.com>: > > > On Jan 3, 8:15 pm, Case Vanhorsen <cas...@gmail.com> wrote: >> Hello, >> >> I discovered an interesting memory allocation behavior on Windows vs. >> Linux. I was testing GMPY on 64-bit Windows when I stumbled into this. >> GMPY replaces the native MPIR memory allocation routines with Python's >> memory allocator. If I enable debugging in GMPY, I get a trace of all >> the memory allocation calls. When I ran the following: >> >> python -mtimeit -n 1 -r 1 -s "import >> gmpy;gmpy.mpz(3)**(2**27);gmpy.set_debug(1)" "a=a*a" 2>temp.txt >> >> and look at the output saved in temp.txt, I see that Linux generated >> approximately 34 memory manager calls but Windows generates over >> 100,000 calls. Most of the Windows allocations are for small (<8K) >> chunks of memory while all the Linux requests are for more than 64K. >> The performance between Linux and Windows is similar. Could it be that >> Windows is not using alloca? >> >> I also think I found another memory allocation bug. If I run the above >> multiplication repeatedly: >> >> python -mtimeit -s "import >> gmpy;gmpy.mpz(3)**(2**27);gmpy.set_debug(1)" "a=a*a" 2>temp.txt >> >> it will eventually crash. In looking at the debug output, I see a >> request to allocate 18446744073709498400 bytes of memory. >> >> I tested with both MPIR 1.2.2 and 1.3.0 and get similar behavior. I'm >> using a custom version of GMPY with some fixes for size_t vs. long >> issues that hasn't been committed but I will try to commit those >> changes later today. > > Hi Case > > That is _very_ useful information and may explain why Windows > performance lgas that on Linux. > > A long time ago - in GMP days - I had to turn of the use of alloca as > I kept getting crashes if I used it. > > I have not tried switching it on in MPIR but I will certainly look at > this again. > > But _alloca is now deprecated on Windows and its replacement requires > a 'free' procedure that alloca doesn't need. It may hence be quite > difficult to take advantage of this in future. It all depends on how > GMP/MPIR use alloca. > > Thanks for the debugging! > > Brian > > -- > > You received this message because you are subscribed to the Google Groups > "mpir-devel" group. > To post to this group, send email to mpir-de...@googlegroups.com. > To unsubscribe from this group, send email to > mpir-devel+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/mpir-devel?hl=en. > > > -- You received this message because you are subscribed to the Google Groups "mpir-devel" group. To post to this group, send email to mpir-de...@googlegroups.com. To unsubscribe from this group, send email to mpir-devel+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/mpir-devel?hl=en.
