svn commit: r333707 - head/sys/x86/x86

[Andriy Gapon]

Author: avg
Date: Thu May 17 10:16:20 2018
New Revision: 333707
URL: https://svnweb.freebsd.org/changeset/base/333707

Log:
  fix a problem with bad performance after wakeup caused by r333321
  
  This change reverts a "while here" part of r333321 that moved clearing
  of suspended_cpus to an earlier place.
  
  Apparently, there can be a problem when modifying (shared) memory before
  restoring proper cache attributes.  So, to be safe, move the clearing to
  the old place.
  
  Many thanks to Johannes Lundberg for bisecting the changes to that
  particular commit and then bisecting the commit to the particular
  change.
  
  Reported by:	many
  Debugged by:	Johannes Lundberg <johalun0 at gmail.com>
  MFC after:	1 week
  X-MFC with:	r333321

Modified:
  head/sys/x86/x86/mp_x86.c

Modified: head/sys/x86/x86/mp_x86.c
==============================================================================
--- head/sys/x86/x86/mp_x86.c	Thu May 17 10:13:18 2018	(r333706)
+++ head/sys/x86/x86/mp_x86.c	Thu May 17 10:16:20 2018	(r333707)
@@ -1457,8 +1457,6 @@ cpususpend_handler(void)
 		 */
 		wbinvd();
 	} else {
-		/* Indicate that we have restarted and restored the context. */
-		CPU_CLR_ATOMIC(cpu, &suspended_cpus);
 #ifdef __amd64__
 		fpuresume(susppcbs[cpu]->sp_fpususpend);
 #else
@@ -1468,6 +1466,9 @@ cpususpend_handler(void)
 		initializecpu();
 		PCPU_SET(switchtime, 0);
 		PCPU_SET(switchticks, ticks);
+
+		/* Indicate that we have restarted and restored the context. */
+		CPU_CLR_ATOMIC(cpu, &suspended_cpus);
 	}
 
 	/* Wait for resume directive */