On Tue, 2012-07-03 at 00:15 +0200, Jan Engelhardt wrote: > On Wednesday 2012-06-27 14:53, Jan Engelhardt wrote: > > > > >On Tuesday 2012-06-26 17:43, Stephen Gallagher wrote: > >> > >>Actually, it most certainly is cached locally. If it was going to LDAP > >>50,000 times, it would take you MUCH longer than 8.5s to get results > >>back. Naturally, looking up results in a local file is faster than > >>getting it out of the SSSD's cache database. However, we have sped this > >>up considerably in SSSD 1.9.0 (currently in beta). We now maintain a > >>second, in-memory cache for requests that is much faster than > >>communicating across the socket to the sssd_nss process and then reading > >>from the database (and processing group nested members). > >> > >>So if you wanted to test our latest nightlies with this program, I think > >>you'd find it responding much faster. > > Unfortunately not. The case is that the users/groups are not in passwd, > but in LDAP. top(1) shows that sssd_nss eats CPU like mad - which would > seem coherent with the assumption that it did not cache negative > entries.
The memory cache does not do negative caching indeed, but sssd_nss does, however it caches negative entries for a very short period of time. However in order to notice this you'd need to have a huge amounts of unexisting entries you query in sequence. > On the whole picture, I am trying out "bindfs", and how long it takes to > extract e.g. a kernel tarball with a given, but fixed over all test > runs, set of bindfs options. It's mostly about repeated getpw*/getgr* > lookups (at least one per created file). Ah I see, you are paying the penalty for a full roundtrip to sssd_nss for each file created. I think we can work on adding some negative caching to the memory cache so to reduce from one call every file to one call every 5 seconds or so. Would you mind opening a ticket for it ? Simo. -- Simo Sorce * Red Hat, Inc * New York _______________________________________________ sssd-devel mailing list sssd-devel@lists.fedorahosted.org https://fedorahosted.org/mailman/listinfo/sssd-devel
