John Ettedgui wrote on 2015/07/30 21:09 -0700:
On Thu, Jul 30, 2015 at 7:34 PM, Qu Wenruo <quwen...@cn.fujitsu.com> wrote:
Hi John,
Thanks for the trace output.
You are welcome, thank you for looking at it!
But it seems that, your root partition is also btrfs, causing a lot of btrfs
trace from your systemd journal.
Oh yes sorry about that.
I actually have 3 partition in btrfs, the problematic one being the
only big one.
Would you mind re-collecting the ftrace without such logging system caused
btrfs trace?
Sure, how would I do that?
This is my first time using ftrace.
I'm not familiar with ftrace either, but your trace is good enough
already, the only thing needed is to avoid using btrfs as root
partition(at least /var/).
My personal recommendation is to use a liveCD or rescue media to do the
trace dump.
Other recommendation is to enable all btrfs trace point, and it seems
that you have already done it while collecting the trace.
BTW, although I'm not quite familiar with ftrace, would you please consider
collect ftrace with function_graph tracer?
Sure, how would I do that one as well?
(I'll look these up in the meantime, I just want to make sure to not
give you something not useful again).
This LWN article should help you, as I'm not so familiar with it either.
https://lwn.net/Articles/370423/
<The function_graph tracer> paragraph.
And the graph_function is btrfs_mount.
Thanks,
Qu
That would help a lot to find which takes the most time.
But it may trace too much things and maybe hard to read.
Thanks,
Qu
Great, thank you!
John
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