Nicolas Pitre <nico@xxxxxxx> writes: > On Wed, 25 Mar 2009, Kjetil Barvik wrote: > >> Nicolas Pitre <nico@xxxxxxx> writes: >> >> > On a 32-bit system, the maximum possible size for an object is less than >> > 4GB, while 64-bit systems may cope with larger objects. Due to this >> > limitation, variables holding object sizes are using an unsigned long >> > type (32 bits on 32-bit systems, or 64 bits on 64-bit systems). >> > >> > When large objects are encountered, and/or people play with large delta >> > depth values, it is possible for the maximum allowed delta size >> > computation to overflow, especially on a 32-bit system. When this >> > occurs, surviving result bits may represent a value much smaller than >> > what it is supposed to be, or even zero. This prevents some objects >> > from being deltified although they do get deltified when a smaller depth >> > limit is used. Fix this by always performing a 64-bit multiplication. >> > >> > Signed-off-by: Nicolas Pitre <nico@xxxxxxx> >> >> I added this patch and rerun the 2 test cases form the table where >> --depth is 20000 and 95000, and got the following result: >> >> --depth=20000 => file size: 19126077 delta: 73814 >> --depth=95000 => file size: 19126087 delta: 73814 >> >> So, it seems that this patch almost fixed the issue. But notice that >> the pack file was 10 bytes larger for the --depth=95000 case. >> >> I made a small perl script to compare the output from 'git verify-pack >> -v' of the 2 idx/pack files, and found the following difference(1) >> (first line from --depth=20000 case, second from --depth=95000): >> >> fe0a6f3e971373590714dbafd087b235ea60ac00 tree 9 19 18921247 731 96a3ec5789504e6d0f90c99fb1937af1ebd58e2d >> fe0a6f3e971373590714dbafd087b235ea60ac00 tree 20 29 18921247 730 12e560f7fb28558b15e3a2008fba860f9a4b2222 > > OK. Apparently, a different base object for that one delta was chosen > between those two runs. > > Is your machine SMP? kjetil ~$ uname -a Linux localhost 2.6.28.4 #26 SMP PREEMPT Tue Feb 10 17:07:14 CET 2009 i686 Intel(R) Core(TM)2 CPU T7200 @ 2.00GHz GenuineIntel GNU/Linux -- kjetil -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
