svn commit: r357476 - head/sys/dev/cxgbe

[Navdeep Parhar]

Author: np
Date: Mon Feb  3 23:30:39 2020
New Revision: 357476
URL: https://svnweb.freebsd.org/changeset/base/357476

Log:
  cxgbe(4): Do not use pack boundary > 512B unless it is explicitly
  requested.
  
  This is a tradeoff between PCIe efficiency during large packet rx and
  packing efficiency during small packet rx.
  
  MFC after:	1 week
  Sponsored by:	Chelsio Communications

Modified:
  head/sys/dev/cxgbe/t4_sge.c

Modified: head/sys/dev/cxgbe/t4_sge.c
==============================================================================
--- head/sys/dev/cxgbe/t4_sge.c	Mon Feb  3 23:25:12 2020	(r357475)
+++ head/sys/dev/cxgbe/t4_sge.c	Mon Feb  3 23:30:39 2020	(r357476)
@@ -589,6 +589,9 @@ t4_sge_extfree_refs(void)
 	return (refs - rels);
 }
 
+/* max 4096 */
+#define MAX_PACK_BOUNDARY 512
+
 static inline void
 setup_pad_and_pack_boundaries(struct adapter *sc)
 {
@@ -635,7 +638,10 @@ setup_pad_and_pack_boundaries(struct adapter *sc)
 	pack = fl_pack;
 	if (fl_pack < 16 || fl_pack == 32 || fl_pack > 4096 ||
 	    !powerof2(fl_pack)) {
-		pack = max(sc->params.pci.mps, CACHE_LINE_SIZE);
+		if (sc->params.pci.mps > MAX_PACK_BOUNDARY)
+			pack = MAX_PACK_BOUNDARY;
+		else
+			pack = max(sc->params.pci.mps, CACHE_LINE_SIZE);
 		MPASS(powerof2(pack));
 		if (pack < 16)
 			pack = 16;