By: Andi Kleen (x.delete@this.y.z), November 21, 2010 2:02 am
Room: Moderated Discussions
slacker (s@lack.er) on 11/20/10 wrote:
---------------------------
>Groo (charlie@semiaccurate.com) on 11/20/10 wrote:
>---------------------------
>>I didn't ask that question, I asked about how much power it consumes when it does
>>miss. By your rather desperate dodge and childish attacks, I can only infer that
>>it is quite a painful number for you to talk about.
>
>The question itself seems misguided; Power consumption can go up, down, or stay the same after a cache miss.
Besides there isn't really a single
cache miss, but lots of different cases:
- depends on the cache level that missed
- depends if the TLB missed too
- depends if it hits local or remote memory (and then
what state the interconnect is in, congested, low
power, remotely cached etc.)
- or if it hits MMIO (like talking to your GPU)
- depends on how congested the memory controller is
- depends if the DIMM has the page open or not
- depends if there's any power management active
in the way that needs to be woken up
etc.etc.pp.
They all will have need power.
---------------------------
>Groo (charlie@semiaccurate.com) on 11/20/10 wrote:
>---------------------------
>>I didn't ask that question, I asked about how much power it consumes when it does
>>miss. By your rather desperate dodge and childish attacks, I can only infer that
>>it is quite a painful number for you to talk about.
>
>The question itself seems misguided; Power consumption can go up, down, or stay the same after a cache miss.
Besides there isn't really a single
cache miss, but lots of different cases:
- depends on the cache level that missed
- depends if the TLB missed too
- depends if it hits local or remote memory (and then
what state the interconnect is in, congested, low
power, remotely cached etc.)
- or if it hits MMIO (like talking to your GPU)
- depends on how congested the memory controller is
- depends if the DIMM has the page open or not
- depends if there's any power management active
in the way that needs to be woken up
etc.etc.pp.
They all will have need power.