3 ms·

Have they grown? I don’t recall that l1 has grown much, and the bigger ones likely have more latency. AMD has some big l3 lately but their l3 has a bit more la

Have they grown? I don’t recall that l1 has grown much, and the bigger ones likely have more latency. AMD has some big l3 lately but their l3 has a bit more latency for it these big caches will help indirect code be a few % less bad but it will still be better by a lot to keep things in l1. now maybe one day with some unforeseen developments, linked lists will be cool again.

torginus 5y ago
L1, not so much, but comparing my old Haswell and my new Zen 2 proc, the L2 size has doubled, and the L3 has has increased from 6MB to a whopping 32MB
- gameswithgo 5y ago
  right but I bet the ratios of cpu latency to l2 and l3 latency have both gotten worse with that growth.
  - torginus 5y ago
    I checked, and it's about the same according to these: https://www.7-cpu.com/cpu/Haswell.html https://www.7-cpu.com/cpu/Haswell.html https://www.7-cpu.com/cpu/Zen.html https://www.7-cpu.com/cpu/Zen.html I think latency has a lot to do with the speed of light - since both of these CPUs run at similar frequencies, you can cover more SRAM cells worth of distance in the one with a denser process geometry, hence you can have access to a larger cache with the same latency.
    - dragontamer 5y ago
      The speed of light is the absolute limit but isn't really a useful measure at any chip-level design. IIRC, its more about capacitance and leakage current. The less capacitance (and 3d finfets / other innovations reduce capacitance), the fewer electrons it will take to "turn on" or "turn off" a transistor. That's why modern process designers are trying more and more exotic shapes to reduce capacitance and reduce the number of electrons that need to be moved anywhere for the "on-off" toggle to happen. Leakage current is the amount of electrons that "leak" even in the offstate (which all CMOS designs are statically in the off-state. Even at 5V / on, there's a complementary transistor that's in the off-state somewhere that theoretically prevents current from flowing). As such, the two sources of current (and therefore power usage) are capacitance (the number of electrons you need to move to turn a transistor from on to off, or vice versa). Or leakage (the number of electrons that flow despite the transistor being nominally off). --------- The lower the leakage, the less power is used. The lower the capacitance, the less power is used AND the quicker the transistor turns on / off (because fewer electrons have to move, so the switch goes from .25 nanoseconds to .1 nanoseconds or whatever).

torginus 5y ago

L1, not so much, but comparing my old Haswell and my new Zen 2 proc, the L2 size has doubled, and the L3 has has increased from 6MB to a whopping 32MB

gameswithgo 5y ago
right but I bet the ratios of cpu latency to l2 and l3 latency have both gotten worse with that growth.
- torginus 5y ago
  I checked, and it's about the same according to these: https://www.7-cpu.com/cpu/Haswell.html https://www.7-cpu.com/cpu/Haswell.html https://www.7-cpu.com/cpu/Zen.html https://www.7-cpu.com/cpu/Zen.html I think latency has a lot to do with the speed of light - since both of these CPUs run at similar frequencies, you can cover more SRAM cells worth of distance in the one with a denser process geometry, hence you can have access to a larger cache with the same latency.
  - dragontamer 5y ago
    The speed of light is the absolute limit but isn't really a useful measure at any chip-level design. IIRC, its more about capacitance and leakage current. The less capacitance (and 3d finfets / other innovations reduce capacitance), the fewer electrons it will take to "turn on" or "turn off" a transistor. That's why modern process designers are trying more and more exotic shapes to reduce capacitance and reduce the number of electrons that need to be moved anywhere for the "on-off" toggle to happen. Leakage current is the amount of electrons that "leak" even in the offstate (which all CMOS designs are statically in the off-state. Even at 5V / on, there's a complementary transistor that's in the off-state somewhere that theoretically prevents current from flowing). As such, the two sources of current (and therefore power usage) are capacitance (the number of electrons you need to move to turn a transistor from on to off, or vice versa). Or leakage (the number of electrons that flow despite the transistor being nominally off). --------- The lower the leakage, the less power is used. The lower the capacitance, the less power is used AND the quicker the transistor turns on / off (because fewer electrons have to move, so the switch goes from .25 nanoseconds to .1 nanoseconds or whatever).