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From Dor Laor <...@scylladb.com>
Subject Re: Meltdown/Spectre Linux patch - Performance impact on Cassandra?
Date Wed, 10 Jan 2018 07:30:15 GMT
Hard to tell from the first 10 google search results which Intel CPUs
has it so I went to ask my /proc/cpuinfo, turns out my >1 year Dell XPS
laptop has it. AWS's i3 has it too.

flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat
pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb
rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology
nonstop_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq dtes64 monitor
ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic
movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm
3dnowprefetch cpuid_fault epb invpcid_single pti intel_pt tpr_shadow vnmi
flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid
mpx rdseed adx smap clflushopt xsaveopt xsavec xgetbv1 xsaves dtherm ida
arat pln pts hwp hwp_notify hwp_act_window hwp_epp


On Tue, Jan 9, 2018 at 11:19 PM, daemeon reiydelle <daemeonr@gmail.com>
wrote:

> Good luck with that. Pcid out since mid 2017 as I recall?
>
>
> Daemeon (Dæmœn) Reiydelle
> USA 1.415.501.0198 <(415)%20501-0198>
>
> On Jan 9, 2018 10:31 AM, "Dor Laor" <dor@scylladb.com> wrote:
>
> 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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>

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