[Bugs] [Bug 1651508] severe drop in response time of simultaneous lookups with other-eager-lock enabled

bugzilla at redhat.com bugzilla at redhat.com
Tue Nov 20 09:05:52 UTC 2018


https://bugzilla.redhat.com/show_bug.cgi?id=1651508

Ashish Pandey <aspandey at redhat.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED



--- Comment #1 from Ashish Pandey <aspandey at redhat.com> ---
Description of problem:
-------------------
when I do a simultaneous lookups using ls from multiple clients, the time taken
to  complete the listing by the last client takes about 11 seconds(other
clients varying from 0.5sec to 8sec). this is in case of a disperse volume
mounted on 4 fuse clients.
However If i disable other-eager-lock, the response time is almost similar and
immediate for all 4 clients ie less than 1 second

This is a serious drop in performance given that the root of volume had about
only 4 directories to be looked up for.

note that this discussion has been going on for sometime in BZ#1530519

Version-Release number of selected component (if applicable):
-------------------
3.12.2-8

How reproducible:
============
always

Steps to Reproduce:
1.create an ec volume say 2x(4+2)
2.mount volume on a client and create 4 entries say 4 directories on root
3.now mount volume on another 3 clients
4. from all clients parallelly issue ls
5. now turn of other-eager-lock and re-issue ls parallelly

Actual results:
-------------
while with step 5 the response by all clients is similar and less than a
second,
with step4 the response time for the last client is as huge as 11sec

Workaround:
Turn off other-eager lock by default

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