Fix high CPU usage in AP-mode

PATCH New Jussi Kivilinna 1 participant 5 messages Feb 12, 2011 Networking drivers (wireless)

Share & tools

Jussi Kivilinna

author

2011-02-12 18:43 UTC #0 lore raw

cover Fix high CPU usage in AP-mode

Series fix high CPU usage noticed in AP-mode. On Intel Atom AP-mode with 100 TU beacon interval was causing CPU usage of ~10%. With these patches CPU usage goes down to ~2%.

---

Jussi Kivilinna (4):
zd1211rw: correct use of usb_bulk_msg on interrupt endpoints
zd1211rw: use async urb for write command
zd1211rw: move async iowrite16v up to callers
zd1211rw: add unlikely to ZD_ASSERT

 drivers/net/wireless/zd1211rw/zd_chip.c |   35 +++++-
 drivers/net/wireless/zd1211rw/zd_def.h  |    2 
 drivers/net/wireless/zd1211rw/zd_usb.c  |  177 +++++++++++++++++++++++++------
 drivers/net/wireless/zd1211rw/zd_usb.h  |    9 +-
 4 files changed, 182 insertions(+), 41 deletions(-)

Jussi Kivilinna

author

2011-02-12 18:43 UTC #1 lore raw

PATCH 1/4 zd1211rw: correct use of usb_bulk_msg on interrupt endpoints

zd1211rw is using usb_bulk_msg() with usb_sndbulkpipe() on interrupt endpoint. However usb_bulk_msg() internally corrects this and makes interrupt URB.

It's better to change usb_bulk_msgs in zd1211rw to usb_interrupt_msg for less confusion.

Signed-off-by Jussi Kivilinna <[email protected]>

---
 drivers/net/wireless/zd1211rw/zd_usb.c |   24 ++++++++++++------------
 1 files changed, 12 insertions(+), 12 deletions(-)

drivers/net/wireless/zd1211rw/zd_usb.c +12 ~~-12~~

index f6df366..7346512 100644
@@ -1634,15 +1634,15 @@ int zd_usb_ioread16v(struct zd_usb *usb, u16 *values,
 
 	udev = zd_usb_to_usbdev(usb);
 	prepare_read_regs_int(usb);
-	r = usb_bulk_msg(udev, usb_sndbulkpipe(udev, EP_REGS_OUT),
-			 req, req_len, &actual_req_len, 50 /* ms */);
+	r = usb_interrupt_msg(udev, usb_sndintpipe(udev, EP_REGS_OUT),
+			      req, req_len, &actual_req_len, 50 /* ms */);
 	if (r) {
 		dev_dbg_f(zd_usb_dev(usb),
-			"error in usb_bulk_msg(). Error number %d\n", r);
+			"error in usb_interrupt_msg(). Error number %d\n", r);
 		goto error;
 	}
 	if (req_len != actual_req_len) {
-		dev_dbg_f(zd_usb_dev(usb), "error in usb_bulk_msg()\n"
+		dev_dbg_f(zd_usb_dev(usb), "error in usb_interrupt_msg()\n"
 			" req_len %d != actual_req_len %d\n",
 			req_len, actual_req_len);
 		r = -EIO;

@@ -1705,16 +1705,16 @@ int zd_usb_iowrite16v(struct zd_usb *usb, const struct zd_ioreq16 *ioreqs,
 	}
 
 	udev = zd_usb_to_usbdev(usb);
-	r = usb_bulk_msg(udev, usb_sndbulkpipe(udev, EP_REGS_OUT),
-			 req, req_len, &actual_req_len, 50 /* ms */);
+	r = usb_interrupt_msg(udev, usb_sndintpipe(udev, EP_REGS_OUT),
+			      req, req_len, &actual_req_len, 50 /* ms */);
 	if (r) {
 		dev_dbg_f(zd_usb_dev(usb),
-			"error in usb_bulk_msg(). Error number %d\n", r);
+			"error in usb_interrupt_msg(). Error number %d\n", r);
 		goto error;
 	}
 	if (req_len != actual_req_len) {
 		dev_dbg_f(zd_usb_dev(usb),
-			"error in usb_bulk_msg()"
+			"error in usb_interrupt_msg()"
 			" req_len %d != actual_req_len %d\n",
 			req_len, actual_req_len);
 		r = -EIO;

@@ -1794,15 +1794,15 @@ int zd_usb_rfwrite(struct zd_usb *usb, u32 value, u8 bits)
 	}
 
 	udev = zd_usb_to_usbdev(usb);
-	r = usb_bulk_msg(udev, usb_sndbulkpipe(udev, EP_REGS_OUT),
-			 req, req_len, &actual_req_len, 50 /* ms */);
+	r = usb_interrupt_msg(udev, usb_sndintpipe(udev, EP_REGS_OUT),
+			      req, req_len, &actual_req_len, 50 /* ms */);
 	if (r) {
 		dev_dbg_f(zd_usb_dev(usb),
-			"error in usb_bulk_msg(). Error number %d\n", r);
+			"error in usb_interrupt_msg(). Error number %d\n", r);
 		goto out;
 	}
 	if (req_len != actual_req_len) {
-		dev_dbg_f(zd_usb_dev(usb), "error in usb_bulk_msg()"
+		dev_dbg_f(zd_usb_dev(usb), "error in usb_interrupt_msg()"
 			" req_len %d != actual_req_len %d\n",
 			req_len, actual_req_len);
 		r = -EIO;

Jussi Kivilinna

author

2011-02-12 18:43 UTC #2 lore raw

PATCH 2/4 zd1211rw: use async urb for write command

In reply to Jussi Kivilinna

Writing beacon to device happen through multiple write command calls. zd_usb_iowrite16v uses synchronous urb call and with multiple write commands in row causes high CPU usage.

This patch makes zd_usb_iowrite16v use asynchronous urb submit within zd_usb.c. zd_usb_iowrite16v_async_start is used to initiate writing multiple commands to device using zd_usb_iowrite16v_async. Each URB is delayed and submitted to device by next zd_usb_iowrite16v_async call or by call to zd_usb_iowrite16v_async_end. URBs submitted by zd_usb_iowrite16v_async have URB_NO_INTERRUPT set and last URB send by zd_usb_iowrite16v_async_end does not. This lower CPU usage when doing writes that require multiple URBs.

Signed-off-by Jussi Kivilinna <[email protected]>

---
 drivers/net/wireless/zd1211rw/zd_usb.c |  162 +++++++++++++++++++++++++++-----
 drivers/net/wireless/zd1211rw/zd_usb.h |    5 +
 2 files changed, 142 insertions(+), 25 deletions(-)

drivers/net/wireless/zd1211rw/zd_usb.c +138 ~~-24~~

index 7346512..c98f6e7 100644
@@ -1156,6 +1156,7 @@ void zd_usb_init(struct zd_usb *usb, struct ieee80211_hw *hw,
 	memset(usb, 0, sizeof(*usb));
 	usb->intf = usb_get_intf(intf);
 	usb_set_intfdata(usb->intf, hw);
+	init_usb_anchor(&usb->submitted_cmds);
 	init_usb_interrupt(usb);
 	init_usb_tx(usb);
 	init_usb_rx(usb);

@@ -1663,13 +1664,104 @@ error:
 	return r;
 }
 
-int zd_usb_iowrite16v(struct zd_usb *usb, const struct zd_ioreq16 *ioreqs,
-	              unsigned int count)
+static void iowrite16v_urb_complete(struct urb *urb)
+{
+	struct zd_usb *usb = urb->context;
+
+	if (urb->status && !usb->cmd_error)
+		usb->cmd_error = urb->status;
+}
+
+static int zd_submit_waiting_urb(struct zd_usb *usb, bool last)
+{
+	int r;
+	struct urb *urb = usb->urb_async_waiting;
+
+	if (!urb)
+		return 0;
+
+	usb->urb_async_waiting = NULL;
+
+	if (!last)
+		urb->transfer_flags |= URB_NO_INTERRUPT;
+
+	usb_anchor_urb(urb, &usb->submitted_cmds);
+	r = usb_submit_urb(urb, GFP_KERNEL);
+	if (r) {
+		usb_unanchor_urb(urb);
+		dev_dbg_f(zd_usb_dev(usb),
+			"error in usb_submit_urb(). Error number %d\n", r);
+		goto error;
+	}
+
+	/* fall-through with r == 0 */
+error:
+	usb_free_urb(urb);
+	return r;
+}
+
+static void zd_usb_iowrite16v_async_start(struct zd_usb *usb)
+{
+	ZD_ASSERT(usb_anchor_empty(&usb->submitted_cmds));
+	ZD_ASSERT(usb->urb_async_waiting == NULL);
+	ZD_ASSERT(!usb->in_async);
+
+	ZD_ASSERT(mutex_is_locked(&zd_usb_to_chip(usb)->mutex));
+
+	usb->in_async = 1;
+	usb->cmd_error = 0;
+	usb->urb_async_waiting = NULL;
+}
+
+static int zd_usb_iowrite16v_async_end(struct zd_usb *usb, unsigned int timeout)
+{
+	int r;
+
+	ZD_ASSERT(mutex_is_locked(&zd_usb_to_chip(usb)->mutex));
+	ZD_ASSERT(usb->in_async);
+
+	/* Submit last iowrite16v URB */
+	r = zd_submit_waiting_urb(usb, true);
+	if (r) {
+		dev_dbg_f(zd_usb_dev(usb),
+			"error in zd_submit_waiting_usb(). "
+			"Error number %d\n", r);
+
+		usb_kill_anchored_urbs(&usb->submitted_cmds);
+		goto error;
+	}
+
+	if (timeout)
+		timeout = usb_wait_anchor_empty_timeout(&usb->submitted_cmds,
+							timeout);
+	if (!timeout) {
+		usb_kill_anchored_urbs(&usb->submitted_cmds);
+		if (usb->cmd_error == -ENOENT) {
+			dev_dbg_f(zd_usb_dev(usb), "timed out");
+			r = -ETIMEDOUT;
+			goto error;
+		}
+	}
+
+	r = usb->cmd_error;
+error:
+	usb->in_async = 0;
+	return r;
+}
+
+static int zd_usb_iowrite16v_async(struct zd_usb *usb,
+				   const struct zd_ioreq16 *ioreqs,
+				   unsigned int count)
 {
 	int r;
 	struct usb_device *udev;
 	struct usb_req_write_regs *req = NULL;
-	int i, req_len, actual_req_len;
+	int i, req_len;
+	struct urb *urb;
+	struct usb_host_endpoint *ep;
+
+	ZD_ASSERT(mutex_is_locked(&zd_usb_to_chip(usb)->mutex));
+	ZD_ASSERT(usb->in_async);
 
 	if (count == 0)
 		return 0;

@@ -1685,17 +1777,23 @@ int zd_usb_iowrite16v(struct zd_usb *usb, const struct zd_ioreq16 *ioreqs,
 		return -EWOULDBLOCK;
 	}
 
-	ZD_ASSERT(mutex_is_locked(&zd_usb_to_chip(usb)->mutex));
-	BUILD_BUG_ON(sizeof(struct usb_req_write_regs) +
-		     USB_MAX_IOWRITE16_COUNT * sizeof(struct reg_data) >
-		     sizeof(usb->req_buf));
-	BUG_ON(sizeof(struct usb_req_write_regs) +
-	       count * sizeof(struct reg_data) >
-	       sizeof(usb->req_buf));
+	udev = zd_usb_to_usbdev(usb);
+
+	ep = usb_pipe_endpoint(udev, usb_sndintpipe(udev, EP_REGS_OUT));
+	if (!ep)
+		return -ENOENT;
+
+	urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!urb)
+		return -ENOMEM;
 
 	req_len = sizeof(struct usb_req_write_regs) +
 		  count * sizeof(struct reg_data);
-	req = (void *)usb->req_buf;
+	req = kmalloc(req_len, GFP_KERNEL);
+	if (!req) {
+		r = -ENOMEM;
+		goto error;
+	}
 
 	req->id = cpu_to_le16(USB_REQ_WRITE_REGS);
 	for (i = 0; i < count; i++) {

@@ -1704,28 +1802,44 @@ int zd_usb_iowrite16v(struct zd_usb *usb, const struct zd_ioreq16 *ioreqs,
 		rw->value = cpu_to_le16(ioreqs[i].value);
 	}
 
-	udev = zd_usb_to_usbdev(usb);
-	r = usb_interrupt_msg(udev, usb_sndintpipe(udev, EP_REGS_OUT),
-			      req, req_len, &actual_req_len, 50 /* ms */);
+	usb_fill_int_urb(urb, udev, usb_sndintpipe(udev, EP_REGS_OUT),
+			 req, req_len, iowrite16v_urb_complete, usb,
+			 ep->desc.bInterval);
+	urb->transfer_flags |= URB_FREE_BUFFER | URB_SHORT_NOT_OK;
+
+	/* Submit previous URB */
+	r = zd_submit_waiting_urb(usb, false);
 	if (r) {
 		dev_dbg_f(zd_usb_dev(usb),
-			"error in usb_interrupt_msg(). Error number %d\n", r);
-		goto error;
-	}
-	if (req_len != actual_req_len) {
-		dev_dbg_f(zd_usb_dev(usb),
-			"error in usb_interrupt_msg()"
-			" req_len %d != actual_req_len %d\n",
-			req_len, actual_req_len);
-		r = -EIO;
+			"error in zd_submit_waiting_usb(). "
+			"Error number %d\n", r);
 		goto error;
 	}
 
-	/* FALL-THROUGH with r == 0 */
+	/* Delay submit so that URB_NO_INTERRUPT flag can be set for all URBs
+	 * of currect batch except for very last.
+	 */
+	usb->urb_async_waiting = urb;
+	return 0;
 error:
+	usb_free_urb(urb);
 	return r;
 }
 
+int zd_usb_iowrite16v(struct zd_usb *usb, const struct zd_ioreq16 *ioreqs,
+			unsigned int count)
+{
+	int r;
+
+	zd_usb_iowrite16v_async_start(usb);
+	r = zd_usb_iowrite16v_async(usb, ioreqs, count);
+	if (r) {
+		zd_usb_iowrite16v_async_end(usb, 0);
+		return r;
+	}
+	return zd_usb_iowrite16v_async_end(usb, 50 /* ms */);
+}
+
 int zd_usb_rfwrite(struct zd_usb *usb, u32 value, u8 bits)
 {
 	int r;

drivers/net/wireless/zd1211rw/zd_usb.h +4 -1

index 2d688f4..9291426 100644
@@ -217,8 +217,11 @@ struct zd_usb {
 	struct zd_usb_rx rx;
 	struct zd_usb_tx tx;
 	struct usb_interface *intf;
+	struct usb_anchor submitted_cmds;
+	struct urb *urb_async_waiting;
+	int cmd_error;
 	u8 req_buf[64]; /* zd_usb_iowrite16v needs 62 bytes */
-	u8 is_zd1211b:1, initialized:1, was_running:1;
+	u8 is_zd1211b:1, initialized:1, was_running:1, in_async:1;
 };
 
 #define zd_usb_dev(usb) (&usb->intf->dev)

Jussi Kivilinna

author

2011-02-12 18:43 UTC #3 lore raw

PATCH 3/4 zd1211rw: move async iowrite16v up to callers

In reply to Jussi Kivilinna

Writing beacon to device happen through multiple write command calls. zd_usb_iowrite16v uses synchronous urb call and with multiple write commands in row causes high CPU usage.

Make asynchronous zd_usb_iowrite16v_async available outside zd_usb.c and use where possible.

This lower CPU usage from ~10% to ~2% on Intel Atom when running AP-mode with 100 TU beacon interval.

Signed-off-by Jussi Kivilinna <[email protected]>

---
 drivers/net/wireless/zd1211rw/zd_chip.c |   35 +++++++++++++++++++++++++------
 drivers/net/wireless/zd1211rw/zd_usb.c  |   11 ++++------
 drivers/net/wireless/zd1211rw/zd_usb.h  |    4 ++++
 3 files changed, 37 insertions(+), 13 deletions(-)

drivers/net/wireless/zd1211rw/zd_chip.c +28 -7

index 54f68f1..a73a305 100644
@@ -142,8 +142,9 @@ int zd_ioread32v_locked(struct zd_chip *chip, u32 *values, const zd_addr_t *addr
 	return 0;
 }
 
-int _zd_iowrite32v_locked(struct zd_chip *chip, const struct zd_ioreq32 *ioreqs,
-	           unsigned int count)
+static int _zd_iowrite32v_async_locked(struct zd_chip *chip,
+				       const struct zd_ioreq32 *ioreqs,
+				       unsigned int count)
 {
 	int i, j, r;
 	struct zd_ioreq16 ioreqs16[USB_MAX_IOWRITE32_COUNT * 2];

@@ -170,7 +171,7 @@ int _zd_iowrite32v_locked(struct zd_chip *chip, const struct zd_ioreq32 *ioreqs,
 		ioreqs16[j+1].addr  = ioreqs[i].addr;
 	}
 
-	r = zd_usb_iowrite16v(&chip->usb, ioreqs16, count16);
+	r = zd_usb_iowrite16v_async(&chip->usb, ioreqs16, count16);
 #ifdef DEBUG
 	if (r) {
 		dev_dbg_f(zd_chip_dev(chip),

@@ -180,6 +181,20 @@ int _zd_iowrite32v_locked(struct zd_chip *chip, const struct zd_ioreq32 *ioreqs,
 	return r;
 }
 
+int _zd_iowrite32v_locked(struct zd_chip *chip, const struct zd_ioreq32 *ioreqs,
+			  unsigned int count)
+{
+	int r;
+
+	zd_usb_iowrite16v_async_start(&chip->usb);
+	r = _zd_iowrite32v_async_locked(chip, ioreqs, count);
+	if (r) {
+		zd_usb_iowrite16v_async_end(&chip->usb, 0);
+		return r;
+	}
+	return zd_usb_iowrite16v_async_end(&chip->usb, 50 /* ms */);
+}
+
 int zd_iowrite16a_locked(struct zd_chip *chip,
                   const struct zd_ioreq16 *ioreqs, unsigned int count)
 {

@@ -187,6 +202,8 @@ int zd_iowrite16a_locked(struct zd_chip *chip,
 	unsigned int i, j, t, max;
 
 	ZD_ASSERT(mutex_is_locked(&chip->mutex));
+	zd_usb_iowrite16v_async_start(&chip->usb);
+
 	for (i = 0; i < count; i += j + t) {
 		t = 0;
 		max = count-i;

@@ -199,8 +216,9 @@ int zd_iowrite16a_locked(struct zd_chip *chip,
 			}
 		}
 
-		r = zd_usb_iowrite16v(&chip->usb, &ioreqs[i], j);
+		r = zd_usb_iowrite16v_async(&chip->usb, &ioreqs[i], j);
 		if (r) {
+			zd_usb_iowrite16v_async_end(&chip->usb, 0);
 			dev_dbg_f(zd_chip_dev(chip),
 				  "error zd_usb_iowrite16v. Error number %d\n",
 				  r);

@@ -208,7 +226,7 @@ int zd_iowrite16a_locked(struct zd_chip *chip,
 		}
 	}
 
-	return 0;
+	return zd_usb_iowrite16v_async_end(&chip->usb, 50 /* ms */);
 }
 
 /* Writes a variable number of 32 bit registers. The functions will split

@@ -221,6 +239,8 @@ int zd_iowrite32a_locked(struct zd_chip *chip,
 	int r;
 	unsigned int i, j, t, max;
 
+	zd_usb_iowrite16v_async_start(&chip->usb);
+
 	for (i = 0; i < count; i += j + t) {
 		t = 0;
 		max = count-i;

@@ -233,8 +253,9 @@ int zd_iowrite32a_locked(struct zd_chip *chip,
 			}
 		}
 
-		r = _zd_iowrite32v_locked(chip, &ioreqs[i], j);
+		r = _zd_iowrite32v_async_locked(chip, &ioreqs[i], j);
 		if (r) {
+			zd_usb_iowrite16v_async_end(&chip->usb, 0);
 			dev_dbg_f(zd_chip_dev(chip),
 				"error _zd_iowrite32v_locked."
 				" Error number %d\n", r);

@@ -242,7 +263,7 @@ int zd_iowrite32a_locked(struct zd_chip *chip,
 		}
 	}
 
-	return 0;
+	return zd_usb_iowrite16v_async_end(&chip->usb, 50 /* ms */);
 }
 
 int zd_ioread16(struct zd_chip *chip, zd_addr_t addr, u16 *value)

drivers/net/wireless/zd1211rw/zd_usb.c +5 -6

index c98f6e7..81e8048 100644
@@ -1674,7 +1674,7 @@ static void iowrite16v_urb_complete(struct urb *urb)
 
 static int zd_submit_waiting_urb(struct zd_usb *usb, bool last)
 {
-	int r;
+	int r = 0;
 	struct urb *urb = usb->urb_async_waiting;
 
 	if (!urb)

@@ -1700,7 +1700,7 @@ error:
 	return r;
 }
 
-static void zd_usb_iowrite16v_async_start(struct zd_usb *usb)
+void zd_usb_iowrite16v_async_start(struct zd_usb *usb)
 {
 	ZD_ASSERT(usb_anchor_empty(&usb->submitted_cmds));
 	ZD_ASSERT(usb->urb_async_waiting == NULL);

@@ -1713,7 +1713,7 @@ static void zd_usb_iowrite16v_async_start(struct zd_usb *usb)
 	usb->urb_async_waiting = NULL;
 }
 
-static int zd_usb_iowrite16v_async_end(struct zd_usb *usb, unsigned int timeout)
+int zd_usb_iowrite16v_async_end(struct zd_usb *usb, unsigned int timeout)
 {
 	int r;

@@ -1749,9 +1749,8 @@ error:
 	return r;
 }
 
-static int zd_usb_iowrite16v_async(struct zd_usb *usb,
-				   const struct zd_ioreq16 *ioreqs,
-				   unsigned int count)
+int zd_usb_iowrite16v_async(struct zd_usb *usb, const struct zd_ioreq16 *ioreqs,
+			    unsigned int count)
 {
 	int r;
 	struct usb_device *udev;

drivers/net/wireless/zd1211rw/zd_usb.h +4 -0

index 9291426..b3df2c8 100644
@@ -273,6 +273,10 @@ static inline int zd_usb_ioread16(struct zd_usb *usb, u16 *value,
 	return zd_usb_ioread16v(usb, value, (const zd_addr_t *)&addr, 1);
 }
 
+void zd_usb_iowrite16v_async_start(struct zd_usb *usb);
+int zd_usb_iowrite16v_async_end(struct zd_usb *usb, unsigned int timeout);
+int zd_usb_iowrite16v_async(struct zd_usb *usb, const struct zd_ioreq16 *ioreqs,
+			    unsigned int count);
 int zd_usb_iowrite16v(struct zd_usb *usb, const struct zd_ioreq16 *ioreqs,
 	              unsigned int count);

Jussi Kivilinna

author

2011-02-12 18:43 UTC #4 lore raw

PATCH 4/4 zd1211rw: add unlikely to ZD_ASSERT

In reply to Jussi Kivilinna

Case assert is violated should be quite unlikely.

Signed-off-by Jussi Kivilinna <[email protected]>

---
 drivers/net/wireless/zd1211rw/zd_def.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

drivers/net/wireless/zd1211rw/zd_def.h +1 -1

index 6ac597f..5463ca9 100644
@@ -45,7 +45,7 @@ typedef u16 __nocast zd_addr_t;
 #ifdef DEBUG
 #  define ZD_ASSERT(x) \
 do { \
-	if (!(x)) { \
+	if (unlikely(!(x))) { \
 		pr_debug("%s:%d ASSERT %s VIOLATED!\n", \
 			__FILE__, __LINE__, __stringify(x)); \
 		dump_stack(); \