Am 24.06.2015 um 16:55 schrieb Nick Fisk:
That kernel probably has the bug where tcp_nodelay is not enabled. That is fixed in Kernel 4.0+, however also in 4.0 blk-mq was introduced which brings two other limitations:-
blk-mq is terrible slow. That's correct. But i wonder about the tcp_nodelay you mention. As 3.18 is a LT kernel it should get fixed upstream.
Can you point me to a commit? Stefan
1.Max queue depth of 128 2.IO’s sizes are restricted/split to 128kb *From:*ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] *On Behalf Of *German Anders *Sent:* 24 June 2015 15:45 *To:* ceph-users *Subject:* kernel 3.18 io bottlenecks? Hi all, Is there any IO botleneck reported on kernel 3.18.3-031803-generic? since I'm having a lot of iowait and the cluster is really getting slow, and actually there's no much going on. I've read some time ago that there were some issues with kern 3.18, so I would like to know what's the 'best' kernel to go with, I'm using Ubuntu 14.04.1LTs and Ceph v0.82. Thanks a lot, Best regards, *German* _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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