Nicolas Pitre <nico@xxxxxxx> wrote: > On Thu, 20 Apr 2006, Shawn Pearce wrote: > > > Based on Linus' comment I changed your patch to just the following. > > It still produced the 46M pack file, so the first hunk apears to > > not have had much of an affect with this data. > > > > From a running time perspective it appears as though this patch is > > making things slightly better, not worse. I ran it a few times > > for each case always using the 46M pack as input for > > "git-repack -a -d -f". > > > > 'next' 137.13 real 95.82 user 25.24 sys > > 'next'+patch 131.62 real 89.35 user 28.56 sys > > > > but even if the running time was an extra 6 seconds I'd still rather > > spend 4% more running time to use 1/2 the storage space. > > > > > > diff --git a/pack-objects.c b/pack-objects.c > > index 09f4f2c..f7d6217 100644 > > --- a/pack-objects.c > > +++ b/pack-objects.c > > @@ -1052,7 +1052,7 @@ static int try_delta(struct unpacked *cu > > if (cur_entry->delta) > > max_size = cur_entry->delta_size-1; > > if (sizediff >= max_size) > > - return -1; > > + return 0; > > delta_buf = diff_delta(old->data, oldsize, > > cur->data, size, &delta_size, max_size); > > if (!delta_buf) > > I can confirm this is indeed the best fix so far. Any "smarter" > solution I could think of did increase the size of the final pack quite > spectacularly and rather unexpectedly with Shawn's repository. Wow. I'm such a trouble maker. *grin* > Of course removing the if (sizediff >= max_size) entirely does produce a > smaller pack (39MB) but it takes about twice the CPU. Eh, that's not worth it. 7M disk space saved for twice the work isn't that good of a tradeoff. I'm not in favor of that version. > With the patch above the Linux kernel pack is 0.3% smaller with 1% more > CPU usage. But like for the diff-delta hash list limiting code this > small overhead is certainly a good compromize to avoid big degradations > in some other cases. Hmm. See the email I just sent. I was seeing a good 10% increase in my own tests on a Linux kernel repository. But I guess I can hope that my test was flawed somehow and it really is closer to a 1% increase in running time, making it more likely that the above fix makes it into GIT. -- Shawn. - : 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