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From Carlos Rolo <r...@pythian.com>
Subject RE: Meltdown/Spectre Linux patch - Performance impact on Cassandra?
Date Sat, 13 Jan 2018 15:55:42 GMT
We are seeing almost no impact on Azure (+1 or 2%). Non-patched OS.

On AWS we don't have any solid data yet.

On 13 Jan 2018 09:46, "Steinmaurer, Thomas" <
thomas.steinmaurer@dynatrace.com> wrote:

Hello Ben,



thanks for the notice. Similar here + others reporting as well:
https://blog.appoptics.com/visualizing-meltdown-aws/





Regards,

Thomas



*From:* Ben Slater [mailto:ben.slater@instaclustr.com]
*Sent:* Freitag, 12. Jänner 2018 23:37

*To:* user@cassandra.apache.org
*Subject:* Re: Meltdown/Spectre Linux patch - Performance impact on
Cassandra?



We’re seeing evidence across our fleet that AWS has rolled something out in
the last 24 hours that has significantly reduce the performance impacts -
back pretty close to pre-patch levels. Yet to see if the impacts come back
with o/s patching on top of the improved hypervisor.



Cheers

Ben







On Thu, 11 Jan 2018 at 05:32 Jon Haddad <jon@jonhaddad.com> wrote:

For what it’s worth, we (TLP) just posted some results comparing pre and
post meltdown statistics: http://thelastpickle.com/blog/2018/
01/10/meltdown-impact-on-latency.html





On Jan 10, 2018, at 1:57 AM, Steinmaurer, Thomas <
thomas.steinmaurer@dynatrace.com> wrote:



m4.xlarge do have PCID to my knowledge, but possibly we need a rather new
kernel 4.14. But I fail to see how this could help anyway, cause this looks
highly Amazon Hypervisor patch related and we do not have the production
instances patched at OS/VM level (yet).



Thomas



*From:* Dor Laor [mailto:dor@scylladb.com <dor@scylladb.com>]
*Sent:* Dienstag, 09. Jänner 2018 19:30
*To:* user@cassandra.apache.org
*Subject:* Re: Meltdown/Spectre Linux patch - Performance impact on
Cassandra?



Make sure you pick instances with PCID cpu capability, their TLB overhead
flush

overhead is much smaller



On Tue, Jan 9, 2018 at 2:04 AM, Steinmaurer, Thomas <
thomas.steinmaurer@dynatrace.com> wrote:

Quick follow up.



Others in AWS reporting/seeing something similar, e.g.:https://twitter.com/
BenBromhead/status/950245250504601600



So, while we have seen an relative CPU increase of ~ 50% since Jan 4, 2018,
we now also have applied a kernel update at OS/VM level on a single node
(loadtest and not production though), thus more or less double patched now.
Additional CPU impact by OS/VM level kernel patching is more or less
negligible, so looks highly Hypervisor related.



Regards,

Thomas



*From:* Steinmaurer, Thomas [mailto:thomas.steinmaurer@dynatrace.com]
*Sent:* Freitag, 05. Jänner 2018 12:09
*To:* user@cassandra.apache.org
*Subject:* Meltdown/Spectre Linux patch - Performance impact on Cassandra?



Hello,



has anybody already some experience/results if a patched Linux kernel
regarding Meltdown/Spectre is affecting performance of Cassandra negatively?



In production, all nodes running in AWS with m4.xlarge, we see up to a 50%
relative (e.g. AVG CPU from 40% => 60%) CPU increase since Jan 4, 2018,
most likely correlating with Amazon finished patching the underlying
Hypervisor infrastructure …



Anybody else seeing a similar CPU increase?



Thanks,

Thomas



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