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* [PATCH net-next 01/16] qlge: Remove irq_cnt
@ 2019-06-17  7:48 Benjamin Poirier
  2019-06-17  7:48 ` [PATCH net-next 02/16] qlge: Remove page_chunk.last_flag Benjamin Poirier
                   ` (17 more replies)
  0 siblings, 18 replies; 46+ messages in thread
From: Benjamin Poirier @ 2019-06-17  7:48 UTC (permalink / raw)
  To: Manish Chopra, GR-Linux-NIC-Dev, netdev

qlge uses an irq enable/disable refcounting scheme that is:
* poorly implemented
	Uses a spin_lock to protect accesses to the irq_cnt atomic variable
* buggy
	Breaks when there is not a 1:1 sequence of irq - napi_poll, such as
	when using SO_BUSY_POLL.
* unnecessary
	The purpose or irq_cnt is to reduce irq control writes when
	multiple work items result from one irq: the irq is re-enabled
	after all work is done.
	Analysis of the irq handler shows that there is only one case where
	there might be two workers scheduled at once, and those have
	separate irq masking bits.

Therefore, remove irq_cnt.

Additionally, we get a performance improvement:
perf stat -e cycles -a -r5 super_netperf 100 -H 192.168.33.1 -t TCP_RR

Before:
628560
628056
622103
622744
627202
[...]
   268,803,947,669      cycles                 ( +-  0.09% )

After:
636300
634106
634984
638555
634188
[...]
   259,237,291,449      cycles                 ( +-  0.19% )

Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
---
 drivers/net/ethernet/qlogic/qlge/qlge.h      |  7 --
 drivers/net/ethernet/qlogic/qlge/qlge_main.c | 98 ++++++--------------
 drivers/net/ethernet/qlogic/qlge/qlge_mpi.c  |  1 -
 3 files changed, 27 insertions(+), 79 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qlge/qlge.h b/drivers/net/ethernet/qlogic/qlge/qlge.h
index ad7c5eb8a3b6..5d9a36deda08 100644
--- a/drivers/net/ethernet/qlogic/qlge/qlge.h
+++ b/drivers/net/ethernet/qlogic/qlge/qlge.h
@@ -1982,11 +1982,6 @@ struct intr_context {
 	u32 intr_dis_mask;	/* value/mask used to disable this intr */
 	u32 intr_read_mask;	/* value/mask used to read this intr */
 	char name[IFNAMSIZ * 2];
-	atomic_t irq_cnt;	/* irq_cnt is used in single vector
-				 * environment.  It's incremented for each
-				 * irq handler that is scheduled.  When each
-				 * handler finishes it decrements irq_cnt and
-				 * enables interrupts if it's zero. */
 	irq_handler_t handler;
 };
 
@@ -2074,7 +2069,6 @@ struct ql_adapter {
 	u32 port;		/* Port number this adapter */
 
 	spinlock_t adapter_lock;
-	spinlock_t hw_lock;
 	spinlock_t stats_lock;
 
 	/* PCI Bus Relative Register Addresses */
@@ -2235,7 +2229,6 @@ void ql_mpi_reset_work(struct work_struct *work);
 void ql_mpi_core_to_log(struct work_struct *work);
 int ql_wait_reg_rdy(struct ql_adapter *qdev, u32 reg, u32 bit, u32 ebit);
 void ql_queue_asic_error(struct ql_adapter *qdev);
-u32 ql_enable_completion_interrupt(struct ql_adapter *qdev, u32 intr);
 void ql_set_ethtool_ops(struct net_device *ndev);
 int ql_read_xgmac_reg64(struct ql_adapter *qdev, u32 reg, u64 *data);
 void ql_mpi_idc_work(struct work_struct *work);
diff --git a/drivers/net/ethernet/qlogic/qlge/qlge_main.c b/drivers/net/ethernet/qlogic/qlge/qlge_main.c
index 6cae33072496..0bfbe11db795 100644
--- a/drivers/net/ethernet/qlogic/qlge/qlge_main.c
+++ b/drivers/net/ethernet/qlogic/qlge/qlge_main.c
@@ -625,75 +625,26 @@ static void ql_disable_interrupts(struct ql_adapter *qdev)
 	ql_write32(qdev, INTR_EN, (INTR_EN_EI << 16));
 }
 
-/* If we're running with multiple MSI-X vectors then we enable on the fly.
- * Otherwise, we may have multiple outstanding workers and don't want to
- * enable until the last one finishes. In this case, the irq_cnt gets
- * incremented every time we queue a worker and decremented every time
- * a worker finishes.  Once it hits zero we enable the interrupt.
- */
-u32 ql_enable_completion_interrupt(struct ql_adapter *qdev, u32 intr)
+static void ql_enable_completion_interrupt(struct ql_adapter *qdev, u32 intr)
 {
-	u32 var = 0;
-	unsigned long hw_flags = 0;
-	struct intr_context *ctx = qdev->intr_context + intr;
-
-	if (likely(test_bit(QL_MSIX_ENABLED, &qdev->flags) && intr)) {
-		/* Always enable if we're MSIX multi interrupts and
-		 * it's not the default (zeroeth) interrupt.
-		 */
-		ql_write32(qdev, INTR_EN,
-			   ctx->intr_en_mask);
-		var = ql_read32(qdev, STS);
-		return var;
-	}
+	struct intr_context *ctx = &qdev->intr_context[intr];
 
-	spin_lock_irqsave(&qdev->hw_lock, hw_flags);
-	if (atomic_dec_and_test(&ctx->irq_cnt)) {
-		ql_write32(qdev, INTR_EN,
-			   ctx->intr_en_mask);
-		var = ql_read32(qdev, STS);
-	}
-	spin_unlock_irqrestore(&qdev->hw_lock, hw_flags);
-	return var;
+	ql_write32(qdev, INTR_EN, ctx->intr_en_mask);
 }
 
-static u32 ql_disable_completion_interrupt(struct ql_adapter *qdev, u32 intr)
+static void ql_disable_completion_interrupt(struct ql_adapter *qdev, u32 intr)
 {
-	u32 var = 0;
-	struct intr_context *ctx;
+	struct intr_context *ctx = &qdev->intr_context[intr];
 
-	/* HW disables for us if we're MSIX multi interrupts and
-	 * it's not the default (zeroeth) interrupt.
-	 */
-	if (likely(test_bit(QL_MSIX_ENABLED, &qdev->flags) && intr))
-		return 0;
-
-	ctx = qdev->intr_context + intr;
-	spin_lock(&qdev->hw_lock);
-	if (!atomic_read(&ctx->irq_cnt)) {
-		ql_write32(qdev, INTR_EN,
-		ctx->intr_dis_mask);
-		var = ql_read32(qdev, STS);
-	}
-	atomic_inc(&ctx->irq_cnt);
-	spin_unlock(&qdev->hw_lock);
-	return var;
+	ql_write32(qdev, INTR_EN, ctx->intr_dis_mask);
 }
 
 static void ql_enable_all_completion_interrupts(struct ql_adapter *qdev)
 {
 	int i;
-	for (i = 0; i < qdev->intr_count; i++) {
-		/* The enable call does a atomic_dec_and_test
-		 * and enables only if the result is zero.
-		 * So we precharge it here.
-		 */
-		if (unlikely(!test_bit(QL_MSIX_ENABLED, &qdev->flags) ||
-			i == 0))
-			atomic_set(&qdev->intr_context[i].irq_cnt, 1);
-		ql_enable_completion_interrupt(qdev, i);
-	}
 
+	for (i = 0; i < qdev->intr_count; i++)
+		ql_enable_completion_interrupt(qdev, i);
 }
 
 static int ql_validate_flash(struct ql_adapter *qdev, u32 size, const char *str)
@@ -2500,21 +2451,22 @@ static irqreturn_t qlge_isr(int irq, void *dev_id)
 	u32 var;
 	int work_done = 0;
 
-	spin_lock(&qdev->hw_lock);
-	if (atomic_read(&qdev->intr_context[0].irq_cnt)) {
-		netif_printk(qdev, intr, KERN_DEBUG, qdev->ndev,
-			     "Shared Interrupt, Not ours!\n");
-		spin_unlock(&qdev->hw_lock);
-		return IRQ_NONE;
-	}
-	spin_unlock(&qdev->hw_lock);
+	/* Experience shows that when using INTx interrupts, the device does
+	 * not always auto-mask the interrupt.
+	 * When using MSI mode, the interrupt must be explicitly disabled
+	 * (even though it is auto-masked), otherwise a later command to
+	 * enable it is not effective.
+	 */
+	if (!test_bit(QL_MSIX_ENABLED, &qdev->flags))
+		ql_disable_completion_interrupt(qdev, 0);
 
-	var = ql_disable_completion_interrupt(qdev, intr_context->intr);
+	var = ql_read32(qdev, STS);
 
 	/*
 	 * Check for fatal error.
 	 */
 	if (var & STS_FE) {
+		ql_disable_completion_interrupt(qdev, 0);
 		ql_queue_asic_error(qdev);
 		netdev_err(qdev->ndev, "Got fatal error, STS = %x.\n", var);
 		var = ql_read32(qdev, ERR_STS);
@@ -2534,7 +2486,6 @@ static irqreturn_t qlge_isr(int irq, void *dev_id)
 		 */
 		netif_err(qdev, intr, qdev->ndev,
 			  "Got MPI processor interrupt.\n");
-		ql_disable_completion_interrupt(qdev, intr_context->intr);
 		ql_write32(qdev, INTR_MASK, (INTR_MASK_PI << 16));
 		queue_delayed_work_on(smp_processor_id(),
 				qdev->workqueue, &qdev->mpi_work, 0);
@@ -2550,11 +2501,18 @@ static irqreturn_t qlge_isr(int irq, void *dev_id)
 	if (var & intr_context->irq_mask) {
 		netif_info(qdev, intr, qdev->ndev,
 			   "Waking handler for rx_ring[0].\n");
-		ql_disable_completion_interrupt(qdev, intr_context->intr);
 		napi_schedule(&rx_ring->napi);
 		work_done++;
+	} else {
+		/* Experience shows that the device sometimes signals an
+		 * interrupt but no work is scheduled from this function.
+		 * Nevertheless, the interrupt is auto-masked. Therefore, we
+		 * systematically re-enable the interrupt if we didn't
+		 * schedule napi.
+		 */
+		ql_enable_completion_interrupt(qdev, 0);
 	}
-	ql_enable_completion_interrupt(qdev, intr_context->intr);
+
 	return work_done ? IRQ_HANDLED : IRQ_NONE;
 }
 
@@ -3557,7 +3515,6 @@ static int ql_request_irq(struct ql_adapter *qdev)
 	ql_resolve_queues_to_irqs(qdev);
 
 	for (i = 0; i < qdev->intr_count; i++, intr_context++) {
-		atomic_set(&intr_context->irq_cnt, 0);
 		if (test_bit(QL_MSIX_ENABLED, &qdev->flags)) {
 			status = request_irq(qdev->msi_x_entry[i].vector,
 					     intr_context->handler,
@@ -4642,7 +4599,6 @@ static int ql_init_device(struct pci_dev *pdev, struct net_device *ndev,
 		goto err_out2;
 	}
 	qdev->msg_enable = netif_msg_init(debug, default_msg);
-	spin_lock_init(&qdev->hw_lock);
 	spin_lock_init(&qdev->stats_lock);
 
 	if (qlge_mpi_coredump) {
diff --git a/drivers/net/ethernet/qlogic/qlge/qlge_mpi.c b/drivers/net/ethernet/qlogic/qlge/qlge_mpi.c
index 957c72985a06..9e422bbbb6ab 100644
--- a/drivers/net/ethernet/qlogic/qlge/qlge_mpi.c
+++ b/drivers/net/ethernet/qlogic/qlge/qlge_mpi.c
@@ -1257,7 +1257,6 @@ void ql_mpi_work(struct work_struct *work)
 	/* End polled mode for MPI */
 	ql_write32(qdev, INTR_MASK, (INTR_MASK_PI << 16) | INTR_MASK_PI);
 	mutex_unlock(&qdev->mpi_mutex);
-	ql_enable_completion_interrupt(qdev, 0);
 }
 
 void ql_mpi_reset_work(struct work_struct *work)
-- 
2.21.0


^ permalink raw reply related	[flat|nested] 46+ messages in thread

end of thread, other threads:[~2019-07-15  9:48 UTC | newest]

Thread overview: 46+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-06-17  7:48 [PATCH net-next 01/16] qlge: Remove irq_cnt Benjamin Poirier
2019-06-17  7:48 ` [PATCH net-next 02/16] qlge: Remove page_chunk.last_flag Benjamin Poirier
2019-06-26  9:12   ` Manish Chopra
2019-06-17  7:48 ` [PATCH net-next 03/16] qlge: Deduplicate lbq_buf_size Benjamin Poirier
2019-06-26  9:24   ` [EXT] " Manish Chopra
2019-06-26 11:37     ` Benjamin Poirier
2019-06-26 15:42       ` Willem de Bruijn
2019-06-28  8:57         ` Benjamin Poirier
2019-06-28 14:56           ` Willem de Bruijn
2019-06-17  7:48 ` [PATCH net-next 04/16] qlge: Remove bq_desc.maplen Benjamin Poirier
2019-06-26  9:31   ` Manish Chopra
2019-06-17  7:48 ` [PATCH net-next 05/16] qlge: Remove rx_ring.sbq_buf_size Benjamin Poirier
2019-06-26  9:36   ` [EXT] " Manish Chopra
2019-06-26 11:39     ` Benjamin Poirier
2019-06-26 15:35       ` Willem de Bruijn
2019-06-17  7:48 ` [PATCH net-next 06/16] qlge: Remove useless dma synchronization calls Benjamin Poirier
2019-06-17  9:44   ` [EXT] " Manish Chopra
2019-06-18  2:51     ` Benjamin Poirier
2019-06-17  7:48 ` [PATCH net-next 07/16] qlge: Deduplicate rx buffer queue management Benjamin Poirier
2019-06-27 10:02   ` [EXT] " Manish Chopra
2019-07-09  2:10     ` Benjamin Poirier
2019-06-17  7:48 ` [PATCH net-next 08/16] qlge: Fix dma_sync_single calls Benjamin Poirier
2019-06-17  7:48 ` [PATCH net-next 09/16] qlge: Remove rx_ring.type Benjamin Poirier
2019-06-17  7:48 ` [PATCH net-next 10/16] qlge: Factor out duplicated expression Benjamin Poirier
2019-06-23 17:59   ` David Miller
2019-06-23 18:00     ` David Miller
2019-06-24  7:52     ` Benjamin Poirier
2019-06-25 18:32       ` Manish Chopra
2019-06-28  8:52         ` Benjamin Poirier
2019-06-17  7:48 ` [PATCH net-next 11/16] qlge: Remove qlge_bq.len & size Benjamin Poirier
2019-06-27 10:47   ` Manish Chopra
2019-07-09  6:52     ` Benjamin Poirier
2019-06-17  7:48 ` [PATCH net-next 12/16] qlge: Remove useless memset Benjamin Poirier
2019-06-17  7:48 ` [PATCH net-next 13/16] qlge: Replace memset with assignment Benjamin Poirier
2019-06-17  7:48 ` [PATCH net-next 14/16] qlge: Update buffer queue prod index despite oom Benjamin Poirier
2019-06-17  7:48 ` [PATCH net-next 15/16] qlge: Refill rx buffers up to multiple of 16 Benjamin Poirier
2019-06-17  7:48 ` [PATCH net-next 16/16] qlge: Refill empty buffer queues from wq Benjamin Poirier
2019-06-27 14:18   ` [EXT] " Manish Chopra
2019-07-10  1:18     ` Benjamin Poirier
2019-06-17 16:49 ` [PATCH net-next 01/16] qlge: Remove irq_cnt Manish Chopra
2019-06-26  8:59 ` Manish Chopra
2019-06-26 11:36   ` Benjamin Poirier
2019-06-26 13:21     ` Manish Chopra
2019-07-05  8:33       ` Benjamin Poirier
2019-07-15  1:40 ` Benjamin Poirier
2019-07-15  9:48   ` Greg Kroah-Hartman

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