2019-kvm-forum/8300-tradeoff-poll-v-notify.html

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   5 <h1>Tradeoff: poll or notify</h1>
   6
   7 <p>
   8   Filler - need to demonstrate:
   9
  10 <p>
  11   polling (server cannot tell client about async changes unless client
  12   polls):
  13   <br>client: NBD_CMD_RESIZE(0)
  14   <br>server: NBD_REPLY_TYPE_RESIZE response, including NBD_REPLY_DONE
  15   <br>do stuff
  16   <br>client: NBD_CMD_RESIZE(0)
  17   <br>server: NBD_REPLY_TYPE_RESIZE response, including NBD_REPLY_DONE
  18 <p>
  19   notify (client registers open-ended command to allow multiple async
  20   server responses as needed):
  21   <br>client: NBD_CMD_RESIZE(NBD_CMD_FLAG_NOTIFY)
  22   <br>do stuff
  23   <br>server: NBD_REPLY_TYPE_RESIZE response, excluding NBD_REPLY_DONE
  24   <br>do stuff
  25   <br>server: NBD_REPLY_TYPE_RESIZE response, excluding NBD_REPLY_DONE
  26 </p>