Show 39 quoted lines
> On Wed, 25 Mar 2009, Kjetil Barvik wrote:
>
>> Nicolas Pitre <nico@cam.org> 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@cam.org>
>>
>> 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?