• FizzyOrange@programming.dev
    1·
    1 hour ago

    Huge speed-ups for the will-it-scale tlb_flush2_threads test - presumably not very representative!

    I wonder how much effect it has on real world workloads.

  • SteveTech@programming.devEnglish
    12·
    1 day ago

    I couldn’t find a hard answer to whether this supports EPYC only, or Ryzen too; so I put together this script to read the CPUID to detect for INVLPGB support according to the AMD64 Programmer’s Manual, and my 7800X3D does not support INVLPGB.

    (Let me know if I’ve made an error though!)

    Code 
    #include <stdio.h>
#include <stdint.h>

int main() {
    uint32_t eax, ebx, ecx, edx;

    eax = 0x80000008;

    __asm__ __volatile__ (
        "cpuid"
        : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
        : "a" (eax)
    );

    printf("EBX: 0x%x\n", ebx);

    if (ebx & (1 << 3)) {
        printf("CPU supports INVLPGB\n");
    } else {
        printf("CPU does not support INVLPGB\n");
    }

    return 0;
}
  • onlinepersona@programming.dev
    301·
    1 day ago

    More surprising is that it’s taken ~4 years for these Linux kernel patches to materialize with Zen 3 having first debuted in late 2020.

    Reminder: Linux kernel funding is 2% of the Linux foundation’s 200M$/year budget.

    Anti Commercial-AI license

    • grue@lemmy.worldEnglish
      30·
      2 days ago

      the Linux kernel hasn’t widely made use of INVLPGB… In part because Intel engineers typically carry out much of the new x86 instruction optimizations within the Linux kernel and Intel processors do not currently support INVLPGB.

      Sounds like AMD needs to fund more kernel development.

      • 𝕽𝖚𝖆𝖎𝖉𝖍𝖗𝖎𝖌𝖍
        2·
        16 hours ago

        Sweet. They’re laptop CPUs, right? Last year, after more than a decade of owning only laptops, I bought two of those micro-PC boxes - mine were Trigkey, but I saw nearly identical ones under other brand names. 16 cores, expandable RAM and NVME… utterly blew my latest 2y/o laptop out of the water, especially after I put 64GB of RAM in one in an orgy of entering a new market of cheap components.

        And now this. I’m loving it.