Re: Ceph Dumpling/Firefly/Hammer SSD/Memstore performance comparison

[Mark Nelson <mnelson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

Hi Alex,

Thanks!  I didn't tweak the sharding settings at all, so they are just 
at the default values:

OPTION(osd_op_num_threads_per_shard, OPT_INT, 2)
OPTION(osd_op_num_shards, OPT_INT, 5)

I don't have really good insight yet into how tweaking these would 
affect single-osd performance.  I know the PCIe SSDs do have multiple 
controllers on-board so perhaps increasing the number of shards would 
improve things, but I suspect that going too high could maybe start 
hurting performance as well.  Have you done any testing here?  It could 
be an interesting follow-up paper.

Mark

On 02/18/2015 02:34 AM, Alexandre DERUMIER wrote:
> Nice Work Mark !
>
> I don't see any tuning about sharding in the config file sample
>
> (osd_op_num_threads_per_shard,osd_op_num_shards,...)
>
> as you only use 1 ssd for the bench, I think it should improve results for hammer ?
>
>
>
> ----- Mail original -----
> De: "Mark Nelson" <mnelson@redhat.com>
> À: "ceph-devel" <ceph-devel@vger.kernel.org>
> Cc: "ceph-users" <ceph-users@lists.ceph.com>
> Envoyé: Mardi 17 Février 2015 18:37:01
> Objet: [ceph-users] Ceph Dumpling/Firefly/Hammer SSD/Memstore performance	comparison
>
> Hi All,
>
> I wrote up a short document describing some tests I ran recently to look
> at how SSD backed OSD performance has changed across our LTS releases.
> This is just looking at RADOS performance and not RBD or RGW. It also
> doesn't offer any real explanations regarding the results. It's just a
> first high level step toward understanding some of the behaviors folks
> on the mailing list have reported over the last couple of releases. I
> hope you find it useful.
>
> Mark
>
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