[Lustre-discuss] Question about adaptive timeouts, not sending early reply

Thomas Roth t.roth at gsi.de
Sat Sep 18 03:34:48 PDT 2010

Hi all,

I'm trying to understand MDT logs and adaptive timeouts. After upgrade
to 1.8.4 and while users believed Lustre to be still in maintenance (=
no activity), the MDT log just shows

Lustre: 19823:0:(service.c:808:ptlrpc_at_send_early_reply()) @@@
Couldn't add any time (42/30), not sending early reply

Now, for historical reasons of running on a very shaky network, we load
the lustre module with

options ptlrpc at_max=6000
options ptlrpc at_history=6000
options ptlrpc at_early_margin=50

Right now however, the MDT reports:

lxmds:~# lctl get_param -n mdt.MDS.mds.timeouts
service : cur  30  worst  76 (at 1284734311, 0d19h33m39s ago)  30 30  30  30

Reading the manual on adaptive timeouts again, I conclude that if the
current estimate for timeout is 30 sec, the MDT is indeed hard pressed
to send an early reply 50 sec before that timeout occurs. The log
messages states something of the like, (42/30).
So, is my assessment correct? Are these log messages just due to the
stupid at_early_margin setting?


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