On Sun, Jun 09, 2013 at 04:37:27PM -0700, Junio C Hamano wrote: > Junio C Hamano <gitster@xxxxxxxxx> writes: > > > Use the commit-queue data structure to implement a priority queue > > of commits sorted by committer date, when handling --date-order. > > The commit-queue structure can also be used as a simple LIFO stack, > > which is a good match for --topo-order processing. > > > > Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx> > > --- > > commit-queue.c | 13 +++++++++++ > > commit-queue.h | 3 +++ > > commit.c | 74 ++++++++++++++++++++++++++++++++++------------------------ > > 3 files changed, 59 insertions(+), 31 deletions(-) > > Peff, I think you were the one who did a priority queue previously, > primarily for performance. The primary reason for this round was so > that I didn't have to touch the revision.c and struct commit in > order to sort by keys in commit-info-slabs and I was not aiming for > performance but a quick and rough benchmarking seems to indicate > that > > - for a small repository like git.git, there is not much difference > in runtime; > > - but it does seem to cut down the memory pressure (less minor > faults). > > Representative runs of "rev-list --date-order v0.99..v1.8.3" on my > box with 'master' and with these patches spend 0.47user/0.04system > with 0.50elapsed (no time change), with 13450 vs 13108 minor faults > (smaller memory use). The performance enhancement of the priority queue came from replacing "commit_list_insert_by_date" calls with insertion into a queue. That drops O(n^2) behavior on the linked-list down to O(n log n), as we have "n" insertions, each causing an O(log n) heapify operation. Around the same time, though, René wrote the linked-list merge sort that powers commit_list_sort_by_date. And topo-sort learned to do O(1) insertions into the unsorted list, and then one O(n log n) sort. So your results are exactly what I would expect: the time should be about the same (due to the same complexity), but the memory is used more compactly (array of pointers instead of linked list of pointers). -Peff -- 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