On Wed, 28 Sep 2011 19:37:18 -0600, Martin Fick wrote:
On Wednesday 28 September 2011 18:59:09 Martin Fick wrote:
Julian Phillips <julian@xxxxxxxxxxxxxxxxx> wrote:
-- snip --
I've created a test repo with ~100k refs/changes/... style refs, and
~40000 refs/heads/... style refs, and checkout can walk the list of
~140k refs seven times in 85ms user time including doing whatever
other
processing is needed for checkout. The real time is only 114ms - but
then my test repo has no real data in.
If I understand what you are saying, it sounds like you do not have a
very good test case. The amount of time it takes for checkout depends
on how long it takes to find a ref with the sha1 that you are on. If
that sha1 is so early in the list of refs that it only took you 7
traversals to find it, then that is not a very good testcase. I think
that you should probably try making an orphaned ref (checkout a
detached head, commit to it), that is probably the worst testcase
since it should then have to search all 140K refs to eventually give
up.
Again, if I understand what you are saying, if it took 85ms for 7
traversals, then it takes approximately 10ms per traversal, that's
only 100/s! If you have to traverse it 140K times, that should work
out to 1400s ~ 23mins.
Well, it's no more than 10ms per traversal - since the rest of the work
presumably takes some time too ...
However, I had forgotten to make the orphaned commit as you suggest -
and then _bang_ 7N^2, it tries seven different variants of each ref
(which is silly as they are all fully qualified), and with packed refs
it has to search for them each time, all to turn names into hashes that
we already know to start with.
So, yes - it is that list traversal.
Does the following help?
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 5e356a6..f0f4ca1 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -605,7 +605,7 @@ static int add_one_ref_to_rev_list_arg(const char
*refname,
int flags,
void *cb_data)
{
- add_one_rev_list_arg(cb_data, refname);
+ add_one_rev_list_arg(cb_data, strdup(sha1_to_hex(sha1)));
return 0;
}
--
Julian
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