Hi Thomas, No clue about AWS, and it is of course highly dependent on hardware, but on CentOS 7 on bare metal, the patched kernel (kernel-3.10.0-693.11.6.el7.x86_64) seems to have a roughly 50% CPU increase compared to an unpatched kernel (kernel-3.10.0-693.11.1.el7.x86_64). On a happier note, the latest mainline kernel from elrepo (kernel-ml-4.14.11-1.el7.elrepo.x86_64) seems to recover the entire performance loss, likely due to recent PCID patches (or the other 3+ years of kernel development).
That's on lab servers though, the numbers here will likely vary a lot based on test setup, and may not be reproducible for production workloads. If you have the infrastructure to test a variety of kernels, I'd be very interested to see your numbers. Thanks, Tom van der Woerdt Site Reliability Engineer Booking.com B.V. Vijzelstraat 66-80 Amsterdam 1017HL Netherlands Direct +31207153426 [image: Booking.com] <http://www.booking.com/> The world's #1 accommodation site 43 languages, 198+ offices worldwide, 120,000+ global destinations, 1,550,000+ room nights booked every day No booking fees, best price always guaranteed Subsidiary of the Priceline Group (NASDAQ: PCLN) On Fri, Jan 5, 2018 at 12:09 PM, Steinmaurer, Thomas < thomas.steinmau...@dynatrace.com> wrote: > 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 > > > The contents of this e-mail are intended for the named addressee only. It > contains information that may be confidential. Unless you are the named > addressee or an authorized designee, you may not copy or use it, or > disclose it to anyone else. If you received it in error please notify us > immediately and then destroy it. Dynatrace Austria GmbH (registration > number FN 91482h) is a company registered in Linz whose registered office > is at 4040 Linz, Austria, Freist > <https://maps.google.com/?q=4040+Linz,+Austria,+Freist%C3%A4dterstra%C3%9Fe+313&entry=gmail&source=g> > ädterstra > <https://maps.google.com/?q=4040+Linz,+Austria,+Freist%C3%A4dterstra%C3%9Fe+313&entry=gmail&source=g> > ße 313 > <https://maps.google.com/?q=4040+Linz,+Austria,+Freist%C3%A4dterstra%C3%9Fe+313&entry=gmail&source=g> >
