NSS: Do not check local users with disabled local_negative_timeout

sssd_nss can set different negative timeout for local users
and groups. However, checking whether user/group is local
is quite expensive operation. We can avoid such operations
if local_negative_timeout is not set.

This fix improve performance(40%) of lookup non-existing
entries in offline mode and with disabled local_negative_timeout.

  sh$ cat pok.sh
  for i in {1..10000}; do
    getent passwd -s sss temp$i
    getent group -s sss temp$i
  done

  #without patch
  sh $time /bin/bash pok.sh
  real    0m41.534s
  user    0m3.580s
  sys     0m14.202s

  #with patch
  sh $time /bin/bash pok.sh
  real    0m26.686s
  user    0m3.292s
  sys     0m13.165s

Resolves:
https://fedorahosted.org/sssd/ticket/3122

Reviewed-by: Petr Cech <pcech@redhat.com>

0 files changed, 0 insertions, 0 deletions