[HN Gopher] Making the most of Apple Silicon power: 2 Core capab...
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       Making the most of Apple Silicon power: 2 Core capabilities (2022)
        
       Author : nateb2022
       Score  : 44 points
       Date   : 2023-07-22 19:15 UTC (3 hours ago)
        
 (HTM) web link (eclecticlight.co)
 (TXT) w3m dump (eclecticlight.co)
        
       | polishTar wrote:
       | Interesting read.
       | 
       | I wonder what went into the decision on the ratio of P to E
       | cores. Naively it seems like more of the die space should be
       | dedicated to E cores since they're so killer for workloads where
       | efficiency or throughput matter. Obviously some jobs can't spread
       | the load across multiple threads and are sensitive to single-
       | threaded latency, but those workloads won't benefit from so many
       | P cores anyways.
        
       | rubatuga wrote:
       | You can force it to E core, using the taskpolicy command.
       | 
       | Here I use it to let my VM run in the background:
       | 
       | https://github.com/yoonsikp/vm_configs/blob/master/power_sav...
        
       | mandalorianer wrote:
       | The link is dead.
        
         | crtasm wrote:
         | Working here, and also now saved to wayback machine.
         | 
         | https://web.archive.org/web/20230722191544/https://eclecticl...
        
       | BeastMachine wrote:
       | While you can't explicitly allocate a process to E cores, I
       | wonder if you'd be able to make a program which floods high QoS
       | processes to saturate E cores until they are full and then launch
       | the desired application into a P core
        
         | treesciencebot wrote:
         | This is a similar hack to what AMD does with their new
         | 3D-series processors with two CCDs (or clusters following this
         | article's terminology). One of them has a higher clock count
         | but the other one has much more L3 cache. Since their target is
         | gamers (at least at the consumer level chips), they basically
         | ship a driver which detects when you launch a game and "parks"
         | the low-cache CCD from being assigned tasks which effectively
         | dispatches your processes to the high-cache ccd.
        
         | Dalewyn wrote:
         | You can't set a process's processor affinity (aka which core(s)
         | the process will execute on)?
        
           | Shekelphile wrote:
           | I don't think it's completely guaranteed that you can choose
           | such things anymore. Some scheduling work has to be done at
           | the hardware level and it's certainly going to be hijacked as
           | heterogeneous CPU micro architecture becomes more pervasive
           | and the gulf of difference in feature set between efficiency
           | and performance cores becomes wider.
        
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       (page generated 2023-07-22 23:00 UTC)