On Thu, Mar 16, 2017 at 10:26:25AM +0000, Zhitao Li wrote: > Hello, everyone, > > > I have been trying to optimize "ls" performance for Glusterfs > recently. My volume is disperse(48 bricks with redundancy 16), and I > mount it with fuse. I create 10000 little files in mount point. Then I > execute "ls" command. In my cluster, it takes about 3 seconds. > > I have a question about fuse_getattr function in "fuse-bridge.c" . Why > need we check whether nodeid is equal to 1? , which means it is the > mount point. It is hard for me to get its meaning. > > (In my case, I find the operation of fuse_getattr takes neer half time > for "ls", that is why I want to know what the check means. ) > > > [http://mail.163.com/js6/s?func=mbox:getMessageData&sid=iCMbFXtmOmngEsSJqWmmoeUvPJvoWUxS&mid=89:1tbiWQWbqlWBWYAhhQAAsE&part=3] > > > > > I try to disable the special check, and then test "ls". It works > normally and have a speedup 2x(about 1.3s without check). The reason > is that in my case, "lookup" cost is much higher than "stat". Without > the special check, getattr goes into "stat" instead of "lookup". > > > Could you tell me the meaning of the special check for "nodeid == 1"? I'm not sure of check in fuse_getattr would account for the huge performance loss/win in your test. The check makes sure that there is a LOOKUP done onf the root of the volume ("/" always has inode "1", GFID "00000000-0000-0000-0000-000000000001"). In the majority of the cases this should be skipped, unless you run your tests withour using a sub-directory. You can use 'gluster volume profile' to get some additional performance statistics. For simple (single brick, or distribution only) volumes, you can also use Wireshark (and "tshark -o srt,...") to see what goes over the (slow) network. HTH, Niels
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