From: Paul Durrant <paul.durrant@citrix.com>
Date: Tue, 19 Jul 2016 13:13:51 +0000 (+0100)
Subject: Reduce priority of suspend thread
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=e58019787f528c0dfc68454108080385c7c7651f;p=people%2Fpauldu%2Fxenbus.git

Reduce priority of suspend thread

In cycles of repeated suspend/resume attempt to make sure other threads
get to run by:

a) Dropping the priority of the suspend thread as low as possible.
b) Deliberately waiting for DPSc on other CPUs to complete before
   checking xenstore again.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
---

diff --git a/src/xenbus/fdo.c b/src/xenbus/fdo.c
index da5cdcc..ce4d4ac 100644
--- a/src/xenbus/fdo.c
+++ b/src/xenbus/fdo.c
@@ -1462,6 +1462,9 @@ FdoSuspend(
     Affinity.Mask = (KAFFINITY)1;
     KeSetSystemGroupAffinityThread(&Affinity, NULL);
 
+    (VOID) KeSetPriorityThread(KeGetCurrentThread(),
+                               LOW_PRIORITY);
+
     Event = ThreadGetEvent(Self);
 
     for (;;) {
@@ -1522,6 +1525,8 @@ FdoSuspend(
 
         __FdoSuspendClearActive(Fdo);
 
+        KeFlushQueuedDpcs();
+
 loop:
         KeSetEvent(&Fdo->SuspendEvent, IO_NO_INCREMENT, FALSE);
     }