[Bugs] [Bug 1499123] Readdirp is considerably slower than readdir on acl clients

bugzilla at redhat.com bugzilla at redhat.com
Fri Oct 6 06:47:46 UTC 2017


https://bugzilla.redhat.com/show_bug.cgi?id=1499123

Susant Kumar Palai <spalai at redhat.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|bugs at gluster.org            |spalai at redhat.com



--- Comment #1 from Susant Kumar Palai <spalai at redhat.com> ---
Description:
We tried a small test on "ACL client". For listing 50k files on root
,it took around 50seconds with readdirp enabled while
the same operation took 5-6 seconds with readdirp disabled. Both the
times md-cache was enabled.

Observation:
We observed that on the 1st test case (readdirp enabled), post readdirp
a getxattr is done. The number of getxattr depends on the number of acl
xattrs (I saw requests on these two: system.posix_acl_default,
system.posix_acl_access). Since need_lookup flag is set, during fuse_resolve
a nameless lookup is executed on the inode(getxattr being inode operation,
hence the nameless lookup). Since md-cache does not serve nameless lookup,
a network hop is needed for each file, costing the time.

With readdirp disabled, the getxattrs are served from md-cache itself(note:
we are discussing the 2nd attempt of ls -l use case).

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