Re: Jewel + kernel 4.4 Massive performance regression (-50%)

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Hello,

Finally, I found time to do some new benchmarks with the latest jewel release (10.2.5) on 4 nodes. Each node has 10 OSDs.

I ran 2 times "ceph tell osd.* bench" over 40 OSDs, here the average speed :

4.2.0-42-generic      97.45 MB/s
4.4.0-53-generic      55.73 MB/s
4.8.15-040815-generic 62.41 MB/s
4.9.0-040900-generic  60.88 MB/s

I have the same behaviour with at least 35 to 40% performance drop between kernel 4.2 and kernel > 4.4

I can do further benches if needed.

Yoann

Le 26/07/2016 à 09:09, Lomayani S. Laizer a écrit :
> Hello,
> do you have journal on disk too ?
> 
> Yes am having journal on same hard disk.
> 
> ok and could you do bench with kernel 4.2 ? just to see if you have better
> throughput. Thanks
> 
> In ubuntu 14 I was running 4.2 kernel. the throughput was the same around 80-90MB/s per osd. I cant tell the difference because each test gives
> the speeds on same range. I did not test kernel 4.4 in ubuntu 14
> 
> 
> --
> Lomayani
> 
> On Tue, Jul 26, 2016 at 9:39 AM, Yoann Moulin <yoann.moulin@xxxxxxx <mailto:yoann.moulin@xxxxxxx>> wrote:
> 
>     Hello,
> 
>     > Am running ubuntu 16 with kernel 4.4-0.31-generic and my speed are similar.
> 
>     do you have journal on disk too ?
> 
>     > I did tests on ubuntu 14 and Ubuntu 16 and the speed is similar. I have around
>     > 80-90MB/s of OSD speeds in both operating systems
> 
>     ok and could you do bench with kernel 4.2 ? just to see if you have better
>     throughput. Thanks
> 
>     > Only issue am observing now with ubuntu 16 is sometime osd fails on rebooting
>     > until i start them manually or adding starting commands in rc.local.
> 
>     in my case, it's a test environment, so I don't have notice those behaviours
> 
>     --
>     Yoann
> 
>     > On Mon, Jul 25, 2016 at 6:45 PM, Yoann Moulin <yoann.moulin@xxxxxxx <mailto:yoann.moulin@xxxxxxx>
>     > <mailto:yoann.moulin@xxxxxxx <mailto:yoann.moulin@xxxxxxx>>> wrote:
>     >
>     >     Hello,
>     >
>     >     (this is a repost, my previous message seems to be slipping under the radar)
>     >
>     >     Does anyone get a similar behaviour to the one described below ?
>     >
>     >     I found a big performance drop between kernel 3.13.0-88 (default kernel on
>     >     Ubuntu Trusty 14.04) or kernel 4.2.0 and kernel 4.4.0.24.14 (default kernel on
>     >     Ubuntu Xenial 16.04)
>     >
>     >     - ceph version is Jewel (10.2.2).
>     >     - All tests have been done under Ubuntu 14.04 on
>     >     - Each cluster has 5 nodes strictly identical.
>     >     - Each node has 10 OSDs.
>     >     - Journals are on the disk.
>     >
>     >     Kernel 4.4 has a drop of more than 50% compared to 4.2
>     >     Kernel 4.4 has a drop of 40% compared to 3.13
>     >
>     >     details below :
>     >
>     >     With the 3 kernel I have the same performance on disks :
>     >
>     >     Raw benchmark:
>     >     dd if=/dev/zero of=/dev/sdX bs=1M count=1024 oflag=direct    => average ~230MB/s
>     >     dd if=/dev/zero of=/dev/sdX bs=1G count=1 oflag=direct       => average ~220MB/s
>     >
>     >     Filesystem mounted benchmark:
>     >     dd if=/dev/zero of=/sdX1/test.img bs=1G count=1              => average ~205MB/s
>     >     dd if=/dev/zero of=/sdX1/test.img bs=1G count=1 oflag=direct => average ~214MB/s
>     >     dd if=/dev/zero of=/sdX1/test.img bs=1G count=1 oflag=sync   => average ~190MB/s
>     >
>     >     Ceph osd Benchmark:
>     >     Kernel 3.13.0-88-generic : ceph tell osd.ID bench => average  ~81MB/s
>     >     Kernel 4.2.0-38-generic  : ceph tell osd.ID bench => average ~109MB/s
>     >     Kernel 4.4.0-24-generic  : ceph tell osd.ID bench => average  ~50MB/s
>     >
>     >     I did new benchmarks then on 3 new fresh clusters.
>     >
>     >     - Each cluster has 3 nodes strictly identical.
>     >     - Each node has 10 OSDs.
>     >     - Journals are on the disk.
>     >
>     >     bench5 : Ubuntu 14.04 / Ceph Infernalis
>     >     bench6 : Ubuntu 14.04 / Ceph Jewel
>     >     bench7 : Ubuntu 16.04 / Ceph jewel
>     >
>     >     this is the average of 2 runs of "ceph tell osd.* bench" on each cluster (2 x 30
>     >     OSDs)
>     >
>     >     bench5 / 14.04 / Infernalis / kernel 3.13 :  54.35 MB/s
>     >     bench6 / 14.04 / Jewel      / kernel 3.13 :  86.47 MB/s
>     >
>     >     bench5 / 14.04 / Infernalis / kernel 4.2  :  63.38 MB/s
>     >     bench6 / 14.04 / Jewel      / kernel 4.2  : 107.75 MB/s
>     >     bench7 / 16.04 / Jewel      / kernel 4.2  : 101.54 MB/s
>     >
>     >     bench5 / 14.04 / Infernalis / kernel 4.4  :  53.61 MB/s
>     >     bench6 / 14.04 / Jewel      / kernel 4.4  :  65.82 MB/s
>     >     bench7 / 16.04 / Jewel      / kernel 4.4  :  61.57 MB/s
>     >
>     >     If needed, I have the raw output of "ceph tell osd.* bench"
>     >
>     >     Best regards
> 
> 


-- 
Yoann Moulin
EPFL IC-IT
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