Meltdown and Spectre patch effects

Questions and Answers : Windows : Meltdown and Spectre patch effects
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rmiller
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Message 1913409 - Posted: 17 Jan 2018, 3:31:17 UTC

My daily output has dropped this week from ~45000 to about 36000. nothing changed but an update . Is it from the repairs to fix Meltdown and Spectre ?? Anybody else notice a drop Since about Jan 10 or so ?
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Message 1913410 - Posted: 17 Jan 2018, 3:40:30 UTC

For the main thread, see https://setiathome.berkeley.edu/forum_thread.php?id=82471
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Message 1917491 - Posted: 7 Feb 2018, 18:37:15 UTC

Regarding effects of the patch, specifically: I have AMD Ryzen (on Linux) and I've noticed some performance issues since the patch. I was not expecting this because I don't see why the CPU app would do many calls to the kernel, which is where the Meltdown patch changes the behavior (by clearing address space).

But, what is really bugging me is that the processor affinity seems to be broken. Anybody else see this???

Previously, I saw each SETI CPU app running on a particular core 99% of the time. Sometimes I would see some switches when I watched for a few minutes. But, generally, the affinity was high, without me doing anything special to encourage it. (I've seen questions about affinity on the forms, before, but never noticed any problems with it, so I don't know what people have done to try to improve affinity in the past.)

Now, however, I never see more than half of the SETI CPU apps using 99% of one core. There is definitely a change. I suspect the loss of affinity may be responsible for performance losses, not just the patch itself.

Does anyone else think this is in indirect result of the Meltdown OS patches?

Does it make sense that the Meltdown patches would ruin affinity? I ask because such an effect was not mentioned in reports I read. I don't see why this would happen.
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Questions and Answers : Windows : Meltdown and Spectre patch effects


 
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