![]() ![]() It builds upon the success of Zen 2, with some significant architectural changes that lead to performance enhancements. ArchitectureĪt the heart of both the desktop and mobile parts is AMD’s Zen 3 architecture. Given the strong reception to Ryzen 4000-powered laptops, we expect a wide variety of manufacturers to build notebooks ranging from slim-and-light to robust mobile gaming rigs. We expect AMD to follow suit with mobile Ryzen 5000, with AMD announcing a 50% increase in laptop models during its CES 2021 keynote. We expect to see more plentiful stock in the next few months.ĪMD’s Ryzen 4000-series mobile processors were announced at CES 2020, and took the better part of the year to proliferate among laptop manufacturers. As of January 2021, however, stock is slowly starting to build back up, especially at brick and mortar retailers like Micro Center. The 5600X and 5800X show up occasionally, but for the most part, you won’t be able to casually buy one of these processors. As is the case with a lot of new PC hardware, Ryzen 5000 series processors are out of stock at most retailers. What is GDDR7? Everything you need to know about next-gen VRAMĪpple M2 Ultra: everything you need to know about Apple’s most powerful chipįinding them for the listed prices is a different story. ![]() I have checked with other Zen 3 CPUs and on other motherboards as well, with these new CPUs it does seem to be always-on STIBP as the default.What is RAM? Here’s everything you need to know So at this point it remains to be seen if the always-on STIBP is intentional with Zen 3 or something that may change with a later CPU microcode update. That later changed with a BIOS/microcode update. Then again, back when AMD Zen 2 first launched we noted that AMD now defaulted to always-on STIBP. STIBP is used for preventing a sibling thread of a core from controlling/influencing the predictions of the other thread. The always-on mode uses STIBP on all tasks where as conditional uses it on SECCOMP processes or indirect branch restricted tasks. Even for the Ryzen 5 3600XT with the latest CPU microcode it's still on conditional STIBP where as Zen 3 is using always-on. That appears to be the main change with Zen 3 from the Spectre mitigation angle is that for STIBP handling is now made always-on rather than conditional. Spectre V2 mitigations on Zen 3 is still using the full AMD retpoline "return trampolines", conditional IBPB (Indirect Branch Prediction Barrier is conditional on SECCOMP or indirect branch restricted tasks), RSB (Return Stack Buffer) filling enabled, and then for the Single-Threaded Indirect Branch Predictors (STIBP) the difference compared to Zen 2 is now the always-on preferred mode. When it comes to mitigation differences with Zen 3, the CPUs still are mitigating Spectre Variant Four "Speculative Store Bypass" with SSB disabling via PRCTL and SECCOMP, Spectre Variant One via usercopy/SWAPGS barriers and _user pointer sanitization, and then Spectre Variant Two is where there is a difference with Zen 3. Tested this round were the AMD Ryzen 5 2600X, Ryzen 5 3600XT, and Ryzen 5 5600X processors with the out-of-the-box/default security mitigations on the Linux 5.9 stable kernel and then re-testing the processors with the "mitigations=off" flag to disable the run-time controlled mitigation settings. Also, unlike Tiger Lake and contrary to rumors, the Zen 3 mitigation performance was in the right direction: disabling the mitigations did help boost the performance as is logical, unlike what we saw with Tiger Lake where now disabling the mitigations hurt the overall performance. Thankfully there is less mitigations to worry about with AMD processors but still even with these new processors there is still a measurable difference in affected workloads between mitigations on and off. The Zen 3 mitigation overhead was compared then to similar AMD Zen 2 and Zen+ processors.Īfter looking last week at the odd state of mitigation performance on Intel's new Tiger Lake processors, the attention shifted to looking at the mitigation overhead for the new AMD Zen 3 processors. For those wondering what the current cost is to the default Spectre mitigation protections on the new AMD Ryzen 5000 series "Zen 3" processors, here are a set of performance tests looking at that overhead with the still relevant mitigations applied by default and then if forcing them off. ![]()
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