Visualizing Meltdown on AWS(blog.appoptics.com) |
Visualizing Meltdown on AWS(blog.appoptics.com) |
I've been noticing major performance changes in our instances and have no idea if it is related to Meltdown or something else.
Google released a blog post specifically on performance: https://blog.google/topics/google-cloud/protecting-our-googl...
It would be nice to have similar transparency from AWS.
Think the constant ragging on Google that appears on HN is becoming a little too much.
On an unrelated note, kind of wish Meltdown had been discovered and exposed separately from Spectre. Intel has managed to weasel its way of out of taking responsibility by implying that this is not a bug and all the other CPUs have similar issues. If they had to respond to Meltdown only, it would have made it a bit harder for their PR and legal department to deny the security and performance implications.
Just a nit, we said [1] that not only are our own applications in production doing fine (even against Variant 2) but also we haven’t been inundated with support calls over the last few months while mitigations were silently rolled out at the host kernel and hypervisor layer. So this class of “Hey, my instances are suddenly way slower, I didn’t do anything” isn’t happening on GCE.
That does not mean that if you perform guest OS updates, don’t have PCID enabled, etc. that you won’t see a degradation. We certainly haven’t tried all permutations of all guests, and the kernel patches are still improving. That’s why we’re actively trying to get everyone to rally behind retpoline, KPTI (with PCID enabled), and so on.
[1] https://www.blog.google/topics/google-cloud/protecting-our-g...
Sorry, I didn't mean to imply that it was Google's customers specifically who should measure and be suspicious. I meant in general, say someone running a service on bare metal outside of any public cloud for example drawing this conclusion - "Google measured the impact of these bugs and mitigations and they didn't see any a significant performance regressions so I probably don't have to worry either".
Also (since you disclosed you work on GCP), I like how Google sponsored Project Zero. Fantastic work and I am sure it will be a great return on that investment. I can certainly see someone thinking about that when deciding to go with GCP vs other solution.
I tried to start a poll but it seems as though my team was just the unlucky one: https://news.ycombinator.com/item?id=16109036
When I read this I thought how weird. It is usually claimed that max performance drop is around 30%. Then I remembered that we are talking in ratios, so a 30% drop in performance(0.7) means a 42% increase in CPU usage(1/0.7=1.42).
How are you trying to measure the performance impact? Are you checking the cloudwatch data or running any specific test?
I am interested to assess the baseline statistics (unpatched so far) and after patching. Any suggestions?
Not sure about RDS
* Impact on M5/C5 instances over similar time period, any difference with the Nitro hypervisor?
* Were Dedicated instances (https://aws.amazon.com/ec2/purchasing-options/dedicated-inst...) patched as well?
* Other examples of software that adapted batching performance automatically with increase in call latency.
>During this same time period, we saw additional CPU increases on our PV instances that had been previously upgraded. This seems to imply some level of HVM patching was occurring on these PV instances around the same time that all pure-HVM instances were patched
This is likely due to Vixen: https://lists.xenproject.org/archives/html/xen-devel/2018-01...
>.... Instead of trying to make a KPTI-like approach work for Xen PV, it seems reasonable to run a copy of Xen within an HVM (or PVH) domU ..... >.... all PV instances in EC2 are using this ....
So the initial bump after the reboot would have been the shim hypervisor which mitigates Vixen. The secondary bump, and bump the native HVM instances saw, would have been the Spectre related stuff.
Based on https://aws.amazon.com/security/security-bulletins/AWS-2018-... - guessing Intel microcode updates
Some stuff won't run in the free tiers anymore and people will have to switch to bigger machines :/
Could we expect Intel to fix the design flaw^Wfeature so that future server appliance (but also desktop) can run without KPTI while still not being affected by Meltdown ? If so, what timeline could we expect ? Say a year for new CPU designs, plus a year to roll-out new machines in datacenter ?
I imagine they’ll try and rush this to get it out there as fast as possible (obviously a lot of people would like to buy CPUs they don’t have this issue for security/performance reasons) but it’s going to take a while. I think years is definitely the minimum.
Meltdown is easy enough (relatively) but Spectre is kind of a disaster. What do you do? Does the branch predictor have to start tagging every branch guess with some sort of process ID to prevent one process from messing with another’s predictions? Tag the cache lines instead so even though the data is in cache you can’t see it because YOUR process didn’t pull it in yet? What a mess.
Its worth pointing out that for their newest designs AMD (and Samsung Exynos) uses the full memory address for branch predictions; no doubt Intel's next design will be doing this.
You can patch various tiers of servers at your own leisure, depending on threat levels and exposure. Measure the impact, capacity plan, etc. Rather than it being forced on you across all tiers because cloud.
Granted, that's the bottom of the barrel (single disk, no IPKVM etc.), but $100 keeps you running for over a year. Better servers are easily available as well, usually a couple of times cheaper than AWS.
Is this a US thing? Based on HN only, I'd never know there's anything between the public cloud and racks of own hardware that you have to wire up and maintain.
I have a bunch of quad core 32 GB machines with dual 480GB SSDs for less than $100/month each (and that's a rather expensive provider with great support, you'll cut the price almost in half with e.g. SoYouStart).
Yes, AWS is convenient, but it's far from the only thing in the world.
Tech stuff isn't hard. The biggest problem is the lack of capacity planning and project communication in tech today. Nimble startup is a euphemism for pure anarchy and chaos. No one wants to plan anything any more.
You're not the first I see saying that, here and on other sites, and this is absolutely wrong.
Shared environments like clouds were singled out because not only were they impacted the worst security wise, they were also going to suffer the most from the fixes.
But even if you only have a regular normal happy server or computer for you alone, remote code execution vulnerabilities aren't unheard of; one your application (be it your own, or a specific one you use, or one of the bazillion stuff running on your system as part of the OS) gets broken and you're a free target. Or anything with a proper scripting surface.
If you're system isn't protected, and any of the application you run has a major security hole, everything will be at risk.
Can see the appeal of AWS for scaling, redundancy, cross region availability, etc., but for long lived services it seems you pay a high price compared to services like Digital Ocean where the per VM cost is significantly lower.
Conceptually it is "pay as you use" by CPU usage, but just rounded into buckets by instance tier.
Of course, there's a lot of underutilization within each bucket, because the granularity isn't per 1% used, but (more or less) per 100% used (aka each core). And also, most applications can't switch instance tiers easily to adapt to demand (though some certainly can).
There is a variety of CPUs. You can "cat /proc/cpuinfo" to see what you got.
>>> most applications can't switch instance tiers easily to adapt to demand (though some certainly can).
Most applications can and do change. Changing the instance type is just a reboot of the machine.
There certainly are, but generally they are the same within the same "class" (ie t2, c5, etc). Example:
- C5: 3.0Ghz custom Xeon processors. - C4: Xeon E5-2666 v3 - C3: Xeon E5-2680 v2 - X1/X1e: Xeon E7-8880 v3 - R4: Xeon E5-2686 v4 - R3: Intel Xeon E5-2670 v2
Etc. The only exception I'm aware of are the burstable instances; AWS's documentation doesn't explicitly guarantee a CPU bin there, it just says "high frequency Xeon".
The difference between an m5.large and an m5.xlarge isn't that you're getting a "faster" processor (meaning higher gigahertz or newer architecture). You're just getting "more" of the same processor (more cores). This is different than on, say, GCP, where you just ask for cores and you can specify if you specifically want a broader generation of Xeon (like Broadwell), but you can't be guaranteed specific chips.
My intention behind saying that most applications can't switch instance tiers is more to point out that most applications aren't prepared to handle node failure, not that there is something intrinsic to the node types which stops them from being able to switch (that'd be much more rare).
Cloud services are not efficient or cheap, they're convenient for the unprepared and haphazard management style that VC's love.
You may still disagree in the end, but you should come to the conclusion that it is not categorically stupid for some companies to choose to pay much more over time so that they can pay a lot less right now.
AWS is not a magical PCI compliance button.
The utter lack of imagination that I see on HN when people are judging others’ technical decisions is kind of hilarious.
Saying that they should run on kumsufi is like explaining to a wholesale company that they should use motorbikes instead of trucks, because motorbikes are cheaper.
Kimsufi is still dedicated hardware (however low-end) that costs 1 figure instead of 5/6. For normal server-grade hardware it's just 5x cheaper than AWS, not 20x.
Again, you're arguing for motorbikes instead of trucks because they are cheaper. Noone care about that, trucks were not selected based on costs in the first place.
We've been taught to build distributed system with unreliable componens and temporaral JIT eventual consistency.
Of course we can run production cloud-scale operations on unreliable systems. And single power supplies without ECC or RAID is pretty low on my list of things that cause outages. Most big hadoop/cassandra shops are running without raid and without redundant power.