svn commit: r356216 - head/sys/dev/ioat

[Alexander Motin]

Author: mav
Date: Tue Dec 31 04:16:52 2019
New Revision: 356216
URL: https://svnweb.freebsd.org/changeset/base/356216

Log:
  Don't spin on cleanup_lock if we are not interrupt.
  
  If somebody else holds that lock, it will likely do the work for us.
  If it won't, then we return here later and retry.
  
  Under heavy load it allows to avoid lock congestion between interrupt and
  polling threads.
  
  MFC after:	1 week
  Sponsored by:	iXsystems, Inc.

Modified:
  head/sys/dev/ioat/ioat.c

Modified: head/sys/dev/ioat/ioat.c
==============================================================================
--- head/sys/dev/ioat/ioat.c	Tue Dec 31 04:00:24 2019	(r356215)
+++ head/sys/dev/ioat/ioat.c	Tue Dec 31 04:16:52 2019	(r356216)
@@ -789,7 +789,12 @@ ioat_process_events(struct ioat_softc *ioat, boolean_t
 	uint32_t completed, chanerr;
 	int error;
 
-	mtx_lock(&ioat->cleanup_lock);
+	if (intr) {
+		mtx_lock(&ioat->cleanup_lock);
+	} else {
+		if (!mtx_trylock(&ioat->cleanup_lock))
+			return;
+	}
 
 	/*
 	 * Don't run while the hardware is being reset.  Reset is responsible