[Gluster-devel] glusterfs and flamegraph

[yinyin]

Hi,all:

I have used FlameGraph to test glusterfs-3.4.2, trace with simple dd.

found that, a lot of cpu consume on frame_fill_groups, My questions:

1. what’s the func of frame_fill_groups? 

2. should it disable by default?

I found the fellow commit add frame_fill_groups.

commit 59ff893d11844eb52453ce4f7f098df05fcde174

Author: Brian Foster <address@hidden>

Date:   Mon Jul 16 13:51:09 2012 -0400

    libglusterfs,mount/fuse: implement gidcache mechanism in fuse-bridge

    

    This change genericizes the cache mechanism implemented in commit

    8efd2845 into libglusterfs/src/gidcache.[ch] and adds fuse-bridge as

    a client. The cache mechanism is fundamentally equivalent, with some

    minor changes:

      - Change cache key from uid_t to uint64_t.

      - Modify the cache add logic to locate and use an entry with a

        matching ID, should it already exist. This addresses a bug in

        the existing mechanism where an expired entry supercedes a newly

        added entry in lookup, causing repeated adds and flushing of a

        cache bucket.

    

    The fuse group cache is disabled by default. It can be enabled via

    the 'gid-timeout' fuse-bridge translator option and accompanying

    mount option (i.e., '-o gid-timeout=1' for a 1s entry timeout).

    

    BUG: 800892