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. Maybe AMD pulls something out of it’s magical hat.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. We think it is very optimistic to believe this will happen at Zen 3. Another rumor floating around is the increase of maximum cores per CCX from four to eight. Zen 3 engineering samples have been spotted on a Chinese forum showing a possible Zen 3 cpu hitting 100-200 Mhz higher clocks than Zen 2. Zen 2 cores (CCX’s) have access to a part of the 元 cache per CCD/CCX, but Zen 3 could have access to the whole cache, increasing speeds and reducing latency. Zen: 14nm, launched in February 2017 (Ryzen 1000 series)īut what about the IPC lift then? The news comes via Redgamingtech that cites they have inside information (still rumors) that the IPC uplift of Zen 3 is not in the range of 5-8% over Zen 2, but greater due too a change in the cache arrangement.Zen 3: 7nm+, design is completed, expected to launch in 2020 (Ryzen 4000 series?).Zen 4: possibly 6nm or 5nm, in design, expected to launch in 2021 (Ryzen 5000 series?).This is followed by Zen 4 in 2021 in 6nm or 5nm. Since Intel is about to launch Comet Lake next month, the Zen 3, 7nm+ architecture could mean a definitive lead for AMD In the CPU market.ĪMD has shared it’s AM4 road map for the coming years mentioning the release of Zen3 in 2020, which is based upon the same architecture as Zen2 but with a refined process 7nm+. With Zen 3 probably launching already in 2020 the gains could be significant if rumors are true. On the contrary they continue developing their architecture. But don’t expect AMD to lean back and rest on their laurels. We have great respect for the way AMD came out of nothing and build such a competitive cpu line up as Ryzen 3000 (Matisse gen.) today. AMD’s cpu sales is going through the roof if we may believe the sales figures of German retailer Mindfactory.
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