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Bug #14117

closed

KRBD : Performance issues with kernel 4.1 series

Added by Vikhyat Umrao over 8 years ago. Updated over 8 years ago.

Status:
Won't Fix
Priority:
Normal
Assignee:
Ilya Dryomov
Category:
-
Target version:
-
% Done:

0%

Source:
other
Tags:
Backport:
Regression:
No
Severity:
3 - minor
Reviewed:
Affected Versions:
ceph-qa-suite:
Crash signature (v1):
Crash signature (v2):

Description

I am finding that it is a specific client that is experiencing this issue. Doing an RBD write from another client has no problem and OK throughput:

rbd map spin1/rbdtest
/dev/rbd0
root@lab2-mon1:/usr/local/ISS/supercore/temp/operations# dd if=/dev/zero of=/dev/rbd0 bs=1M count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 4.36296 s, 240 MB/s

Versus

root@e1:~# dd if=/dev/zero of=/dev/rbd0 bs=1M count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 46.3618 s, 22.6 MB/s

This problem looks like in kernel with 4.1 series :

kernel 4.1.6 is slow
kernel 4.1.15 is slow

As it is good with:

kernel 3.19 is fast
kernel 4.2.8 is fast

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