FS#38843 - [linux] 3.13: Load average never goes below 2

Attached to Project: Arch Linux
Opened by Júlio Dutra (dutrajulio) - Saturday, 08 February 2014, 18:38 GMT
Last edited by Jan de Groot (JGC) - Thursday, 11 May 2017, 09:45 GMT
Task Type Bug Report
Category Upstream Bugs
Status Closed
Assigned To Tobias Powalowski (tpowa)
Architecture x86_64
Severity Medium
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 1
Private No

Details

Description:
15 minutes load average grows until 2 and stays

Additional info:
* linux-3.13
* System with bcache->luks->hdd


Steps to reproduce:
Start the system in any level (rescue or graphical) then observes the 15 minutes load average growing. The load stops near 2 at my case and never decays. I see this only in a linux-3.13 with bcache+luks. I searched about and not found any similar case.
This task depends upon

Closed by  Jan de Groot (JGC)
Thursday, 11 May 2017, 09:45 GMT
Reason for closing:  No response
Comment by Gerardo Exequiel Pozzi (djgera) - Sunday, 09 February 2014, 17:36 GMT
Linux 3.12.x works good? Please report to upstream, there is nothing to do here.
Comment by Thomas Bächler (brain0) - Tuesday, 11 February 2014, 10:57 GMT
I cannot reproduce this with LUKS. Can you get the same behaviour with bcache only?
Comment by Heinz Hölzl (hlzhnz) - Monday, 07 April 2014, 14:06 GMT
I have the problem too on a machine using bcache + brtrfs. With kernel 3.12 all works fine, with 3.13 i have load average of 2, with linux-3.14-3 (from testing) the problem still exists.

I do not use LUKS.


Comment by Júlio Dutra (dutrajulio) - Saturday, 12 April 2014, 11:57 GMT
Sorry, i was very busy in the last months and couldn't reply. Yes, i forgot this, i use btrfs too!

I think someone is already addressing this problem or something like this. See: http://comments.gmane.org/gmane.linux.kernel.bcache.devel/2499

Maybe i can apply the patches today. If so, i will put the results here.
Comment by Júlio Dutra (dutrajulio) - Saturday, 12 April 2014, 13:51 GMT
I applied the patch above. The load now remains at 1 and the message "bcache_writebac:155 blocked for more than XXX seconds" not occur anymore. A little better, but IMHO not completely solved yet.
Comment by Thomas Bächler (brain0) - Saturday, 12 April 2014, 16:01 GMT
If this problem is an isolated problem in bcache, I would like to wait until a final solution is applied upstream before doing anything in our kernel package.
Comment by Júlio Dutra (dutrajulio) - Sunday, 13 April 2014, 11:41 GMT
I agree. Maybe this bug report can be closed.
Comment by Heinz Hölzl (hlzhnz) - Wednesday, 16 April 2014, 08:12 GMT
Now i removed bcache and all works fine. Too bad, bcache ist a nice thing

Kernel 3.14.1-1-ARCH, btrfs
Comment by Júlio Dutra (dutrajulio) - Sunday, 20 April 2014, 11:41 GMT
Another topic about that: http://permalink.gmane.org/gmane.linux.kernel.bcache.devel/2492

For some reason bcache writeback is running even when cache mode is writethrough.

Execute "echo 0 > /sys/block/bcache0/bcache/writeback_running" has the same effect of patch applied before.
Comment by Tobias Powalowski (tpowa) - Wednesday, 13 August 2014, 07:08 GMT
Status on 3.16?
Comment by Júlio Dutra (dutrajulio) - Wednesday, 13 August 2014, 14:55 GMT
Sometimes the load average is normal but at majority of time stays at 1. I switched from btrfs to xfs but nothing changed.
Comment by Doug Newgard (Scimmia) - Wednesday, 13 May 2015, 20:21 GMT
Someone on the forum is reporting a similar issue as fixed in 4.0.2, can anyone here confirm?

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