[HN Gopher] How to Make Rust Leak Memory (Also: How to Make It S...
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       How to Make Rust Leak Memory (Also: How to Make It Stop)
        
       Author : fasterthanlime
       Score  : 10 points
       Date   : 2022-06-15 20:02 UTC (2 hours ago)
        
 (HTM) web link (fly.io)
 (TXT) w3m dump (fly.io)
        
       | mwcampbell wrote:
       | This is super tangential, but does anyone else find it sad that
       | operating systems receive keys from USB keyboards using polling
       | rather than interrupts? Wouldn't comprehensive use of interrupts
       | rather than polling allow the processor to move to a lower-power
       | state? No wonder our closed smartphones are more battery-
       | efficient than our open PCs.
        
         | Findecanor wrote:
         | There is a common misconception that the host would be polling
         | the keyboard state, always. It is actually polling to ask the
         | device if it has a new packet to send. If the keyboard's state
         | hasn't changed then there is no new packet and there isn't any
         | input processing done by the CPU. (This scheme is actually
         | called "Interrupt" in the USB standard, BTW)
         | 
         | The host polls because _it_ is in control of scheduling all
         | activity on the bus. It must be scheduled because there can be
         | multiple devices (and multiple interfaces per device) with
         | different characteristics on the same bus, and they must be
         | kept from interfering one-another.
        
         | TingPing wrote:
         | You think polling at 500hz has a meaningful impact on your CPU?
        
         | [deleted]
        
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       (page generated 2022-06-15 23:02 UTC)