[SSSD] No negative cache with sssd_nss

Jan Engelhardt jengelh at inai.de
Tue Jul 3 02:02:25 UTC 2012


On Tuesday 2012-07-03 03:44, Simo Sorce wrote:
>
>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.

How short is the default?

>However in order to notice this you'd need to have a huge amounts of
>unexisting entries you query in sequence.

It's a very bounded set of user/groups (< 5).

>> 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 ?

The default trac interface is horrible. There just is no link on the
frontpage to submit an issue. (Compare with sourceforge project pages
where there is clearly "support"/"tracker". Or people accept stuff on
mailing lists.)



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