4 ms·
What a horrible test. They tested without hyperthreading turned on. Spectre and Meltdown are risks BECAUSE of hyperthreading. It makes zero sense to test the pe
by AmVess 8y ago
What a horrible test. They tested without hyperthreading turned on. Spectre and Meltdown are risks BECAUSE of hyperthreading. It makes zero sense to test the performance impact of the fixes with the major component of the problem turned off.
- BeeOnRope 8y agoNeither Spectre nor Meltdown are related to hyperthreading.
- tux3 8y agoYou're right that Spectre and Meltdown are not related to SMT, but that doesn't invalidate the wider point about hyper-threading and side-channel issues I think. Parent may have simply meant TLBleed/L1TF (Foreshadow) instead of Meltdown/Spectre.
- BeeOnRope 8y agoI'm not trying to invalidate any wider point about hyperthreading, and the original article wasn't trying to make one. It was specifically about Spectre and Meltdown mitigations which are unrelated to hyperthreading, so testing with or without hyperthreading is fine. Bringing up hyperthreading here is like bringing up how a diet high in salt is unhealthy, someone pointing out that salt has nothing to do with the original article, and then a final comment "Yeah, but that doesn't invalidate the wider point that we should consume less salt!".
- sigi45 8y agoI will look it up later but i thought hyperthreading increases it. Perhaps i'm mixing something up but i thought that intel removed smt from the newer generations (is removing it) because of it.
- BeeOnRope 8y agoThere have been other recent vulnerabilities, like the ax/ah thing described in [1] or TLBleed that have relied on SMT, but not Meltdown or the original Spectre variants. [1] http://gallium.inria.fr/blog/intel-skylake-bug/ http://gallium.inria.fr/blog/intel-skylake-bug/
- 51lver 8y agoRunning the chips in less than ideal performance settings does seem fishy. I wonder if the perf gap is wider or narrower with HT on.