Just another data point: I'm not seeing this on my locally built (but not with the attached patch) 1.9.1:
real 0m41.409s user 0m3.358s sys 0m3.683s finished round 1 real 0m35.036s user 0m3.441s sys 0m3.658s finished round 2 real 0m44.344s user 0m3.363s sys 0m3.728s finished round 3 real 0m40.930s user 0m3.465s sys 0m3.973s finished round 4 I had to reduce the number of inner iterations to 300 because my machine is slow. The variance in the above numbers is because there's a bunch of stuff running on this machine. Chris On 2011/08/08 11:21, Greg Hudson wrote: > On Mon, 2011-08-08 at 11:22 -0400, Jonathan Reams wrote: >> I did some performance testing on our test KDC and was able to >> reproduce the performance issue with 1.9.1. > > I found a regression which would affect these tests, but I'm not sure it > accounts for your global performance issues. > > The KDC in krb5 1.9 isn't supposed to be using an on-disk replay cache, > but due to a bug, it is actually opening and reading a replay cache for > every TGS request, which is significantly less efficient than the 1.8 > behavior (using a replay cache which stays open for the lifetime of the > KDC). > > In a test which runs in under five minutes, this regression produces > visible O(n^2) performance characteristics. This would not necessarily > account for performance degradation over hours, as the performance drag > of the replay cache should become stable after five minutes. It's > possible that the constant drag was enough to cause the KDC to fall > behind on the request load, but it's also possible that there's a second > problem which isn't so easily reproduced. > > I've attached a patch. Note that there is a second, in-memory > "lookaside" cache with O(n^2) performance characteristics in the short > term, which holds queries for up to two minutes. You may see a slight > degradation in performance in test cases due to this. You can > temporarily rebuild the kdc directory with "make clean; > CPPFLAGS=-DNOCACHE" if you want to remove this variable from your > performance tests. > > > > > ________________________________________________ > Kerberos mailing list [email protected] > https://mailman.mit.edu/mailman/listinfo/kerberos ________________________________________________ Kerberos mailing list [email protected] https://mailman.mit.edu/mailman/listinfo/kerberos
