Call to FsRtlRegisterUncProviderEx introduces performance penalty

NTFSD
1

Hi there!

We have a full file system driver (not a filter) which was using FsRtlRegisterUncProvider (without Ex) to deal with UNC translations. However, on a recent change, we started using FsRtlRegisterUncProviderEx and we are experiencing a big performance penalty that goes away by just using the older UNC registration routine.

  1. Can all the I/O going through MUP be the reason for such a performance degradation?
  2. Has anyone seen this before?
  3. Is there any drawback on keep using the older registration routine on recent versions of Windows to workaround the performance issue?

Thanks in advance.