1. 05 Aug, 2019 4 commits
  2. 03 Aug, 2019 35 commits
  3. 01 Aug, 2019 1 commit
    • Jon Maloy's avatar
      tipc: reduce risk of wakeup queue starvation · 7c5b4205
      Jon Maloy authored
      In commit 365ad353 ("tipc: reduce risk of user starvation during
      link congestion") we allowed senders to add exactly one list of extra
      buffers to the link backlog queues during link congestion (aka
      "oversubscription"). However, the criteria for when to stop adding
      wakeup messages to the input queue when the overload abates is
      inaccurate, and may cause starvation problems during very high load.
      
      Currently, we stop adding wakeup messages after 10 total failed attempts
      where we find that there is no space left in the backlog queue for a
      certain importance level. The counter for this is accumulated across all
      levels, which may lead the algorithm to leave the loop prematurely,
      although there may still be plenty of space available at some levels.
      The result is sometimes that messages near the wakeup queue tail are not
      added to the input queue as they should be.
      
      We now introduce a more exact algorithm, where we keep adding wakeup
      messages to a level as long as the backlog queue has free slots for
      the corresponding level, and stop at the moment there are no more such
      slots or when there are no more wakeup messages to dequeue.
      
      Fixes: 365ad353 ("tipc: reduce risk of user starvation during link congestion")
      Reported-by: default avatarTung Nguyen <tung.q.nguyen@dektech.com.au>
      Acked-by: default avatarYing Xue <ying.xue@windriver.com>
      Signed-off-by: default avatarJon Maloy <jon.maloy@ericsson.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      7c5b4205