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How Do Spectre/Meltdown Fixes Affect The Linux Kernel? (phoronix.com)
"Using the newly minted Linux 4.19 feature code, fresh benchmarks were carried out looking at the performance cost of Spectre/Meltdown/Foreshadow mitigations on Intel Xeon v. AMD EPYC CPUs," writes an anonymous Slashdot reader:
Workloads affected by these CPU vulnerabilities mainly deal with I/O and frequent kernel calls while CPU bound tests are still found to be minimally impacted. When toggling these mitigations on Linux 4.19, Intel Xeon CPUs were found to be 10~15% slower with the default kernel while AMD EPYC CPUs dropped to about 5% slower.
The only problem with AMD processors is they don't implement transactional memory operations.
I can understand your concern if you need this for research, but as an optimization, transactional memory has so far proved pretty underwhelming.
When all you have is a hammer, every problem starts to look like a thumb.
Basically, this completely erases Intel's single thread advantage over AMD. I am sure that Intel will fix their speculative execution blunders in some future processor generation, I suspect it can be fixed without any slowdown, just re-engineering and maybe a bunch more transistors in the cache and dispatch logic. But by the time Intel does fix it AMD will already be shipping 7nm processors. So I don't see Intel getting back into the high end processor lead any time soon.
It's a one-two-three whammy for Intel. Almost starting to feel sorry for them. Almost.
When all you have is a hammer, every problem starts to look like a thumb.
The only problem with AMD processors is they don't implement transactional memory operations.
Aside some very specific use cases, transactional memory does not offer much in terms of performance. Moreover, transactional memory helps a lot with Timing Side Channel Attacks against the kernel. For example: https://www.blackhat.com/docs/...
Indeed. And this partially explained why Intel was ahead of AMD speed-wise. They played fast and loose and f*** the customer.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
Where's the BeOS port you promised us in 1997?
Il n'y a pas de Planet B.
So I don't see Intel getting back into the high end processor lead any time soon.
Why are you implying they aren't in the lead? Users can chose optimised code paths at the expense of security. We do this all the time and the trade off is in terms of risk vs reward. Just like when you log into your online bank instead of walking to the branch and manually doing your banking you make the same trade-off.
Users don't need to run Spectre / Meltdown mitigations, not only from a choice point of view, but also because the risk profile is so incredibly low for the vast majority of use cases it doesn't actually make any sense for a typical user. End result: Speed.
If my workloads weren't often multi-threaded then Intel would still be the performance king, but lets face it... my next CPU will be a Ryzen.