[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 <bfoster at redhat.com>
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


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