queue-4.14/dlm-don-t-swamp-the-cpu-with-callbacks-queued-during.patch

   1 From 51f6e15573004ce9a32edcb5f2b19fa3fba8ca8e Mon Sep 17 00:00:00 2001
   2 From: Bob Peterson <rpeterso@redhat.com>
   3 Date: Thu, 8 Nov 2018 14:04:50 -0500
   4 Subject: dlm: Don't swamp the CPU with callbacks queued during recovery
   5
   6 [ Upstream commit 216f0efd19b9cc32207934fd1b87a45f2c4c593e ]
   7
   8 Before this patch, recovery would cause all callbacks to be delayed,
   9 put on a queue, and afterward they were all queued to the callback
  10 work queue. This patch does the same thing, but occasionally takes
  11 a break after 25 of them so it won't swamp the CPU at the expense
  12 of other RT processes like corosync.
  13
  14 Signed-off-by: Bob Peterson <rpeterso@redhat.com>
  15 Signed-off-by: David Teigland <teigland@redhat.com>
  16 Signed-off-by: Sasha Levin <sashal@kernel.org>
  17 ---
  18  fs/dlm/ast.c | 10 ++++++++++
  19  1 file changed, 10 insertions(+)
  20
  21 diff --git a/fs/dlm/ast.c b/fs/dlm/ast.c
  22 index 07fed838d8fd..15fa4239ae9f 100644
  23 --- a/fs/dlm/ast.c
  24 +++ b/fs/dlm/ast.c
  25 @@ -290,6 +290,8 @@ void dlm_callback_suspend(struct dlm_ls *ls)
  26                 flush_workqueue(ls->ls_callback_wq);
  27  }
  28
  29 +#define MAX_CB_QUEUE 25
  30 +
  31  void dlm_callback_resume(struct dlm_ls *ls)
  32  {
  33         struct dlm_lkb *lkb, *safe;
  34 @@ -300,15 +302,23 @@ void dlm_callback_resume(struct dlm_ls *ls)
  35         if (!ls->ls_callback_wq)
  36                 return;
  37
  38 +more:
  39         mutex_lock(&ls->ls_cb_mutex);
  40         list_for_each_entry_safe(lkb, safe, &ls->ls_cb_delay, lkb_cb_list) {
  41                 list_del_init(&lkb->lkb_cb_list);
  42                 queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
  43                 count++;
  44 +               if (count == MAX_CB_QUEUE)
  45 +                       break;
  46         }
  47         mutex_unlock(&ls->ls_cb_mutex);
  48
  49         if (count)
  50                 log_rinfo(ls, "dlm_callback_resume %d", count);
  51 +       if (count == MAX_CB_QUEUE) {
  52 +               count = 0;
  53 +               cond_resched();
  54 +               goto more;
  55 +       }
  56  }
  57
  58 --
  59 2.19.1
  60