[PATCH AUTOSEL 3.18 05/61] dlm: Don't swamp the CPU with callbacks queued during recovery

Sasha Levin
2019-01-28T16:26:40Z

From: Bob Peterson <rpeterso@redhat.com>

[ Upstream commit 216f0efd19b9cc32207934fd1b87a45f2c4c593e ]

Before this patch, recovery would cause all callbacks to be delayed,
put on a queue, and afterward they were all queued to the callback
work queue. This patch does the same thing, but occasionally takes
a break after 25 of them so it won't swamp the CPU at the expense
of other RT processes like corosync.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/dlm/ast.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/fs/dlm/ast.c b/fs/dlm/ast.c
index dcea1e37a1b7..f18619bc2e09 100644
--- a/fs/dlm/ast.c
+++ b/fs/dlm/ast.c
@@ -290,6 +290,8 @@ void dlm_callback_suspend(struct dlm_ls *ls)
flush_workqueue(ls->ls_callback_wq);
}

+#define MAX_CB_QUEUE 25
+
void dlm_callback_resume(struct dlm_ls *ls)
{
struct dlm_lkb *lkb, *safe;
@@ -300,15 +302,23 @@ void dlm_callback_resume(struct dlm_ls *ls)
if (!ls->ls_callback_wq)
return;

+more:
mutex_lock(&ls->ls_cb_mutex);
list_for_each_entry_safe(lkb, safe, &ls->ls_cb_delay, lkb_cb_list) {
list_del_init(&lkb->lkb_cb_list);
queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
count++;
+ if (count == MAX_CB_QUEUE)
+ break;
}
mutex_unlock(&ls->ls_cb_mutex);

if (count)
log_rinfo(ls, "dlm_callback_resume %d", count);
+ if (count == MAX_CB_QUEUE) {
+ count = 0;
+ cond_resched();
+ goto more;
+ }
}

--
2.19.1