Originally posted by EphemeralEft
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The Performance Impact Of Intel's Register File Data Sampling "RFDS" Mitigation
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The 14900K is a hybrid processor with both P and E cores, while the vulnerability should only affect performance on E cores. Yet even your single-threaded benchmarks show small differences here (I'd expect the scheduler to quickly put and keep them on the 'best' core, which in this situation would always be a P-core).
Would it be possible to set up E-core-only benchmarks to really expose the effects? You should be able to 'park' all but one of the P-cores, then use processor affinity or some aspect of cgroups to finish the job.
This ability (to test only P or only E cores of a hybrid -- or for that matter only C or only c-cores of a modern AMD processor) is becoming a significant need, hopefully it will eventually become a routine feature of the test suite.
Please include geomean charts even in little throwaway posts like this I really prefer to see 3 geomean charts -- single-threaded tests, MT tests, and all together.
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Originally posted by filbo View PostThe 14900K is a hybrid processor with both P and E cores, while the vulnerability should only affect performance on E cores. Yet even your single-threaded benchmarks show small differences here (I'd expect the scheduler to quickly put and keep them on the 'best' core, which in this situation would always be a P-core).
Would it be possible to set up E-core-only benchmarks to really expose the effects? You should be able to 'park' all but one of the P-cores, then use processor affinity or some aspect of cgroups to finish the job.
This ability (to test only P or only E cores of a hybrid -- or for that matter only C or only c-cores of a modern AMD processor) is becoming a significant need, hopefully it will eventually become a routine feature of the test suite.
Please include geomean charts even in little throwaway posts like this I really prefer to see 3 geomean charts -- single-threaded tests, MT tests, and all together.
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CVE-2024-LOL-CPU: The "ChipperChuckle" Vulnerability
Description: The "ChipperChuckle" vulnerability affects the widest possible range of CPUs (meaning all of them,) allowing malicious actors to execute arbitrary code without proper authorization. This vulnerability stems from the fundamental ability of CPUs to execute instructions, including those intended for malicious purposes, such as malware.
Impact: Attackers can exploit this vulnerability to run code on affected systems, potentially leading to data theft, system compromise, and other malicious activities. The ability of CPUs to execute code, while essential for their functionality, poses a significant security risk when exploited by attackers.
Solution: Use a pen and some paper instead of a CPU.
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Originally posted by loganj View Posti thought that microcode mitigation can impact performance as well. so using mitigation=off might be useless with newer microcode.
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Originally posted by filbo View PostWould it be possible to set up E-core-only benchmarks to really expose the effects? You should be able to 'park' all but one of the P-cores, then use processor affinity or some aspect of cgroups to finish the job.
Need to know how it affects P-cores vs E-cores.
Originally posted by filbo View PostPlease include geomean charts even in little throwaway posts like this I really prefer to see 3 geomean charts -- single-threaded tests, MT tests, and all together.
In this case, I wouldn't expect the impact to differ much, between single-threaded and multithreaded. I do find the idea of 3 Geomean charts a bit weird, since the mix of single & multi is pretty arbitrary, in any given article. I'd say: show us separate lightly-threaded and heavily-threaded geomeans, when they differ substantially. Otherwise, just having one is fine.
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Originally posted by Forge View PostIf you have an N100-based miniPC around, it's not hard to test this mitigation, since all the processor cores are E-cores.- Test the impact on a P-core (or hybrid processor with E-cores disabled).
- Test the impact on an E-core processor.
From what I've heard, you can't disable all P-cores on a hybrid CPU, hence the need for an E-only CPU. Without an E-only CPU, it should be almost as good if you just use affinity to restrict the benchmark to run on E-cores (i.e. via a utility like taskset), since the mitigation only affect user/kernel transitions, which should only be happening on the cores where you allow the benchmark to run.
Originally posted by Forge View PostI bought one to use as a router, but had to retire/replace it due to Realtek NICs hanging all the time.
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Originally posted by coder View PostThe ideal performance comparison would involve:- Test the impact on a P-core (or hybrid processor with E-cores disabled).
- Test the impact on an E-core processor.
From what I've heard, you can't disable all P-cores on a hybrid CPU, hence the need for an E-only CPU. Without an E-only CPU, it should be almost as good if you just use affinity to restrict the benchmark to run on E-cores (i.e. via a utility like taskset), since the mitigation only affect user/kernel transitions, which should only be happening on the cores where you allow the benchmark to run.
That's a shame, not least because Intel's Ethernet controllers are buggy, too.
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Originally posted by Forge View PostI'm currently planning for a bigger, better virtualization host in the future, and I'll be putting a dual 10Gbps NIC in, instead.
Industrail thin mini-ITX motherboard featuring Intel's N97 quad core processor ideal for industrial control system, factory automation, retail POS, or panel PCs. High speed connectivity with two 2.5GbE LAN, a M.2 2230 slot for WIFI, M.2 3042/3052 with nano SIM socket for 5G/LTE. Also supports triple displays via two HDMI 2.0, a USB 3.2 Type-C with DisplayPort 1.4 support, or a LVDS/eDP header.
It's about the only one I've seen that accepts DDR5 DIMMs and its NVMe slot is x2 (unlike some that are only x1!). It's a little pricey, but it's meant to be industrial-grade. Not sure if it supports in-band ECC, but the manual doesn't say so.
Here are some Thin mini-ITX cases:
I like the thin aesthetic. That PT13 even has a mount for a 2.5" drive. I imagine they could make it even smaller without.Last edited by coder; 07 April 2024, 02:35 AM.
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