[6/6] qeth: Fix HiperSockets performance regression

Submitted by frank.blaschka@de.ibm.com on Jan. 21, 2013, 12:30 p.m.

Details

Message ID 20130121123037.755818924@de.ibm.com
State Accepted
Delegated to: David Miller
Headers show

Commit Message

frank.blaschka@de.ibm.com Jan. 21, 2013, 12:30 p.m.
From: Stefan Raspl <raspl@linux.vnet.ibm.com>

Commit 46d3ceab "tcp: TCP Small Queues" has severly degraded
performance for single connection RR workloads on HiperSockets with
MTU >=16K due to a conflict of the TCP Small Queues approach with our
buffer scan threshold which releases buffers not frequently enough yet.
This fix restores performance to the same level as before cited commit.

Signed-off-by: Stefan Raspl <raspl@linux.vnet.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
---
 drivers/s390/net/qeth_core_main.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


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--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -4700,7 +4700,7 @@  static int qeth_qdio_establish(struct qe
 	init_data.output_sbal_addr_array = (void **) out_sbal_ptrs;
 	init_data.output_sbal_state_array = card->qdio.out_bufstates;
 	init_data.scan_threshold =
-		(card->info.type == QETH_CARD_TYPE_IQD) ? 8 : 32;
+		(card->info.type == QETH_CARD_TYPE_IQD) ? 1 : 32;
 
 	if (atomic_cmpxchg(&card->qdio.state, QETH_QDIO_ALLOCATED,
 		QETH_QDIO_ESTABLISHED) == QETH_QDIO_ALLOCATED) {