Quinn
AAdmincraft
•Created by Flexz on 11/15/2023 in #questions
AMD V-Cache
Ya flex that’s what makes sense to me though I’m going off so little information that’s it’s like 🤷♂️ could make sense could not
117 replies
AAdmincraft
•Created by Flexz on 11/15/2023 in #questions
AMD V-Cache
Personally I would optimize for miss penalty because do you trust random plug-in developers to organize their plugins in ways which make sense? I don’t. Maybe it just takes one plug-in to be accessing way more memory than it needs to be for all the benefits of the v-cache to go out the window
117 replies
AAdmincraft
•Created by Flexz on 11/15/2023 in #questions
AMD V-Cache
For OP, this kind of seems like a YOLO decision to me unless you have an estimate for the V-cache miss rate vs the miss rate for non v-cache and with the miss penalty for non v-cache and the added miss penalty for v-cache. Because I mean if you are running 100 Gb of memory it seems kind of hard to eyeball it like, maybe the benefits from increased hit chance for L3 would be better for v-cache but if v-cache is only 96 mb then who’s to say? Personally it seems like because in minecraft the main bottleneck problem is the main thread having to wait, then maybe it’s better to look at worst case scenario which might be the main thread having to wait for a memory request due to a cache miss. If in the worst case v-cache miss penalty is considerably worse then maybe that’s a hard sell because the cache miss is when you really have the opportunity for the CPU to just be stalling
117 replies
AAdmincraft
•Created by Flexz on 11/15/2023 in #questions
AMD V-Cache
^ more often than not meaning probably always in most situations
117 replies
AAdmincraft
•Created by Flexz on 11/15/2023 in #questions
AMD V-Cache
RAS would probably not be important for reads generally because reads are often more than one word so the row wouldn’t need to be specified every time. Though for a first word latency RAS definitely matters because just like CAS you need to set RAS. Though I think the problem is that first word latency isn’t the pivotal quantifier here. Because reads are more often than not going to be more than one word.
117 replies
AAdmincraft
•Created by Flexz on 11/15/2023 in #questions
AMD V-Cache
I’m kinda confused by the logic here. If you’re referring to first word latency off cuff then that’s a combination of both cas and ras. Though why only focus on first word latency? Are you assuming that queries would only be 64 bit for some reason I’m kind of confused? Because if more than 64 bits then fast page mode so row access time might not matter. Though in that case the actual bus speed won’t matter because the memory can set up the next operation at the same time as it’s bussing the information back. It’s not a time loss if you need to get several words from the memory. So saying that cas and memory speed both matter especially here is a bit confusing. It would be either CAS and RAS + memory speed ( I assume you mean bus speed) matter or just CAS matters in fast page mode with a more than 64 bit query.
117 replies