console: usbkbd: Improve TFTP booting performance

PATCH Superseded Jim Lin 2 participants 6 messages Jun 27, 2013 – Jun 28, 2013 Tegra architecture support

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Jim Lin

author

2013-06-27 09:45 UTC #0 lore raw

PATCH v3 1/2 console: usbkbd: Improve TFTP booting performance

TFTP booting is observed a little bit slow, especially when a USB keyboard is installed.
The fix is to move polling to every second if we sense that other task like TFTP boot is running.

Signed-off-by Jim Lin <[email protected]>

---
Changes in v2:
1. Change configuration name from CONFIG_CTRLC_POLL_MS to CONFIG_CTRLC_POLL_S.
2. New code will be executed only when CONFIG_CTRLC_POLL_S is defined in configuration header file.
3. Add description in README.console.
Changes in v3:
1. Move changes to common/usb_kbd.c and doc/README.usb
2. Rename config setting to CONFIG_USBKB_TESTC_PERIOD.
3. Remove slow response on USB-keyboard input when TFTP boot is not running.

 common/usb_kbd.c |   20 ++++++++++++++++++++
 doc/README.usb   |   15 ++++++++++++++-
 2 files changed, 34 insertions(+), 1 deletions(-)

common/usb_kbd.c +20 -0

index 3174b5e..25bf677 100644
@@ -121,6 +121,11 @@ struct usb_kbd_pdata {
 	uint8_t		flags;
 };
 
+#ifdef CONFIG_USBKB_TESTC_PERIOD
+/* The period of time between two calls of usb_kbd_testc(). */
+static unsigned long kbd_testc_tms;
+#endif
+
 /* Generic keyboard event polling. */
 void usb_kbd_generic_poll(void)
 {

@@ -366,6 +371,21 @@ static int usb_kbd_testc(void)
 	struct usb_device *usb_kbd_dev;
 	struct usb_kbd_pdata *data;
 
+#ifdef CONFIG_USBKB_TESTC_PERIOD
+	/*
+	 * T is the time between two calls of usb_kbd_testc().
+	 * If CONFIG_USBKB_TESTC_PERIOD ms < T < 1000 ms,
+	 * it implies other task like TFTP boot is running,
+	 * then we reduce polling to every second
+	 * to improve TFTP booting performance.
+	 */
+	if ((get_timer(kbd_testc_tms) >=
+	    (CONFIG_USBKB_TESTC_PERIOD * CONFIG_SYS_HZ / 1000)) &&
+	    (get_timer(kbd_testc_tms) < CONFIG_SYS_HZ))
+		return 0;
+	else
+		kbd_testc_tms = get_timer(0);
+#endif
 	dev = stdio_get_by_name(DEVNAME);
 	usb_kbd_dev = (struct usb_device *)dev->priv;
 	data = usb_kbd_dev->privptr;

doc/README.usb +14 -1

index b4c3ef5..ff4ee6f 100644
@@ -80,7 +80,20 @@ CONFIG_USB_UHCI	    defines the lowlevel part.A lowlevel part must be defined
 CONFIG_USB_KEYBOARD enables the USB Keyboard
 CONFIG_USB_STORAGE  enables the USB storage devices
 CONFIG_USB_HOST_ETHER	enables USB ethernet adapter support
-
+CONFIG_USBKB_TESTC_PERIOD defines the average time (in ms) between two calls
+			of usb_kbd_testc() when TFTP boot is not running
+			In u-boot console, usb_kbd_testc() will be called
+			periodically.
+			When this configuration is defined and other task like
+			TFTP boot is running, USB keyboard will be polled less
+			frequently and will be polled every second.
+			This is to improve TFTP booting performance when USB
+			keyboard is installed.
+			In u-boot console, no impact on keyboard input if TFTP
+			boot is not running.
+			Example:
+			Define the following in configuration header file
+			#define CONFIG_USBKB_TESTC_PERIOD 100
 
 USB Host Networking
 ===================

Signature · 1 line

1.7.7

Jim Lin

author

2013-06-27 09:45 UTC #1 lore raw

PATCH v3 2/2 config: Tegra: Improve TFTP booting performance

Add CONFIG_USBKB_TESTC_PERIOD configuration if CONFIG_USB_KEYBOARD is defined in platform configuration file.

Signed-off-by Jim Lin <[email protected]>

---
Changes in v2:
- None
Changes in v3:
- Add CONFIG_USBKB_TESTC_PERIOD in include/configs/tegra-common-post.h

 include/configs/tegra-common-post.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

include/configs/tegra-common-post.h +1 -0

index 6ed2fde..ee341ef 100644
@@ -128,6 +128,7 @@
 #ifdef CONFIG_USB_KEYBOARD
 #define STDIN_KBD_USB ",usbkbd"
 #define CONFIG_SYS_USB_EVENT_POLL
+#define CONFIG_USBKB_TESTC_PERIOD 100
 #define CONFIG_PREBOOT			"usb start"
 #else
 #define STDIN_KBD_USB ""

Signature · 1 line

1.7.7

Stephen Warren

2013-06-27 18:20 UTC #2 lore raw

PATCH v3 1/2 console: usbkbd: Improve TFTP booting performance

In reply to Jim Lin

Quoted 13 lines · Jim Lin

TFTP booting is observed a little bit slow, especially when a USB keyboard is installed.
The fix is to move polling to every second if we sense that other task like TFTP boot is running.
common/usb_kbd.c +5 -0
 
+#ifdef CONFIG_USBKB_TESTC_PERIOD
+	/*
+	 * T is the time between two calls of usb_kbd_testc().
+	 * If CONFIG_USBKB_TESTC_PERIOD ms < T < 1000 ms,
+	 * it implies other task like TFTP boot is running,

common/usb_kbd.c static int usb_kbd_testc(void) · line 388

Quoted 10 lines

common/usb_kbd.c +10 -0

+	 * then we reduce polling to every second
+	 * to improve TFTP booting performance.
+	 */
+	if ((get_timer(kbd_testc_tms) >=
+	    (CONFIG_USBKB_TESTC_PERIOD * CONFIG_SYS_HZ / 1000)) &&
+	    (get_timer(kbd_testc_tms) < CONFIG_SYS_HZ))
+		return 0;
+	else
+		kbd_testc_tms = get_timer(0);
+#endif

I have a hard time understanding why the fact that "some other task is running" implies anything at all re: how often usb_kbd_testc() would be called.

It's quite possible that "some other task" is extremely fine-grained, and calls usb_kbd_testc() every 0.1ms, and would be severely negatively affected by usb_kbd_testc() taking a long time to execute.

Conversly, it's quite possible that "some other task" is quite granular, and calls usb_kbd_testc() a wide intervals, say every 200ms.

So, I think this change keys of entirely the wrong thing.

Shouldn't the TFTP process (or use of USB networking?) or other long-running tasks that do check for keyboard IO simply set some flag to indicate to usb_kbd_testc() that it should run at a reduced rate, or even just have those long-running processses call usb_kbd_testc() at a reduced rate themselves?

Jim Lin

author

2013-06-28 03:59 UTC #3 lore raw

PATCH v3 1/2 console: usbkbd: Improve TFTP booting performance

Quoted 20 lines · Stephen Warren

Quoted 19 lines · Jim Lin
TFTP booting is observed a little bit slow, especially when a USB keyboard is installed.
The fix is to move polling to every second if we sense that other task like TFTP boot is running.
common/usb_kbd.c +11 -0
 
+#ifdef CONFIG_USBKB_TESTC_PERIOD
+	/*
+	 * T is the time between two calls of usb_kbd_testc().
+	 * If CONFIG_USBKB_TESTC_PERIOD ms < T < 1000 ms,
+	 * it implies other task like TFTP boot is running,
+	 * then we reduce polling to every second
+	 * to improve TFTP booting performance.
+	 */
+	if ((get_timer(kbd_testc_tms) >=
+	    (CONFIG_USBKB_TESTC_PERIOD * CONFIG_SYS_HZ / 1000)) &&
+	    (get_timer(kbd_testc_tms) < CONFIG_SYS_HZ))

Quoted 8 lines

common/usb_kbd.c static int usb_kbd_testc(void) · line 388
Quoted 4 lines
common/usb_kbd.c +4 -0
+		return 0;
+	else
+		kbd_testc_tms = get_timer(0);
+#endif
I have a hard time understanding why the fact that "some other task is running" implies anything at all re: how often usb_kbd_testc() would be called.

In my case it takes about 95 ms on Tegra20 and Tegra114 for usb_kbd_testc() to be called periodically.
So I set CONFIG_USBKB_TESTC_PERIOD to 100.
Like I said, if CONFIG_USBKB_TESTC_PERIOD ms < T < 1000 ms we reduce polling (send command to USB keyboard to check is there any key pressed) to every second.

Quoted 8 lines

It's quite possible that "some other task" is extremely fine-grained, and calls usb_kbd_testc() every 0.1ms, and would be severely negatively affected by usb_kbd_testc() taking a long time to execute.
Conversly, it's quite possible that "some other task" is quite granular, and calls usb_kbd_testc() a wide intervals, say every 200ms.

Quoted 7 lines

So, I think this change keys of entirely the wrong thing.
Shouldn't the TFTP process (or use of USB networking?) or other long-running tasks that do check for keyboard IO simply set some flag to indicate to usb_kbd_testc() that it should run at a reduced rate, or even just have those long-running processses call usb_kbd_testc() at a reduced rate themselves?

To fix in usb_kbd_testc() is easier because this issue happens only when USB keyboard is installed and CONFIG_USB_KEYBOARD is defined.

--
nvpublic

Stephen Warren

2013-06-28 05:09 UTC #4 lore raw

PATCH v3 1/2 console: usbkbd: Improve TFTP booting performance

Quoted 29 lines · Jim Lin

Quoted 20 lines · Stephen Warren
Quoted 19 lines · Jim Lin
TFTP booting is observed a little bit slow, especially when a USB keyboard is installed.
The fix is to move polling to every second if we sense that other task like TFTP boot is running.
common/usb_kbd.c +11 -0
 
+#ifdef CONFIG_USBKB_TESTC_PERIOD
+	/*
+	 * T is the time between two calls of usb_kbd_testc().
+	 * If CONFIG_USBKB_TESTC_PERIOD ms < T < 1000 ms,
+	 * it implies other task like TFTP boot is running,
+	 * then we reduce polling to every second
+	 * to improve TFTP booting performance.
+	 */
+	if ((get_timer(kbd_testc_tms) >=
+	    (CONFIG_USBKB_TESTC_PERIOD * CONFIG_SYS_HZ / 1000)) &&
+	    (get_timer(kbd_testc_tms) < CONFIG_SYS_HZ))
Quoted 8 lines
common/usb_kbd.c static int usb_kbd_testc(void) · line 388
Quoted 4 lines
common/usb_kbd.c +4 -0
+		return 0;
+	else
+		kbd_testc_tms = get_timer(0);
+#endif
I have a hard time understanding why the fact that "some other task is running" implies anything at all re: how often usb_kbd_testc() would be called.

Quoted 6 lines

In my case it takes about 95 ms on Tegra20 and Tegra114 for usb_kbd_testc() to be called periodically.
So I set CONFIG_USBKB_TESTC_PERIOD to 100.
Like I said, if CONFIG_USBKB_TESTC_PERIOD ms < T < 1000 ms we reduce polling (send command to USB keyboard to check is there any key pressed) to every second.

OK, so I think how this works is: If nothing is happening, then usb_kbd_testc() is repeatedly called back-to-back with no delay between. So, if the time between two calls to usb_kbd_testc() is much longer than the time it takes to execute it once, then something else is going on, and hence the code should skip some calls to usb_kbd_testc().

If that's how this works, then why require CONFIG_USBKBD_TESTC_PERIOD to be set? Why not simply measure the time between when usb_kbd_testc() returns, and when it is re-entered? If it's very short, nothing else is happening. If it's very long, something else is happening. That is a far more direct measurement, and is immune to e.g. CPU frequency differences in a way that a static value for CONFIG_USBKBD_TESTC_PERIOD is not.

Also, any kind of time measurement doesn't solve the issue I mentioned
re: how granular the other task is.

Finally, if you're sitting at the command-prompt, is usb_kbd_testc() used at all? How does regular typing using a USB keyboard interact with this code; will typing react fast, but CTRL-C react slowly?

Jim Lin

author

2013-06-28 10:01 UTC #5 lore raw

PATCH v3 1/2 console: usbkbd: Improve TFTP booting performance

Quoted 43 lines · Stephen Warren

Quoted 29 lines · Jim Lin
Quoted 20 lines · Stephen Warren
Quoted 19 lines · Jim Lin
TFTP booting is observed a little bit slow, especially when a USB keyboard is installed.
The fix is to move polling to every second if we sense that other task like TFTP boot is running.
common/usb_kbd.c +11 -0
 
+#ifdef CONFIG_USBKB_TESTC_PERIOD
+	/*
+	 * T is the time between two calls of usb_kbd_testc().
+	 * If CONFIG_USBKB_TESTC_PERIOD ms < T < 1000 ms,
+	 * it implies other task like TFTP boot is running,
+	 * then we reduce polling to every second
+	 * to improve TFTP booting performance.
+	 */
+	if ((get_timer(kbd_testc_tms) >=
+	    (CONFIG_USBKB_TESTC_PERIOD * CONFIG_SYS_HZ / 1000)) &&
+	    (get_timer(kbd_testc_tms) < CONFIG_SYS_HZ))
Quoted 8 lines
common/usb_kbd.c static int usb_kbd_testc(void) · line 388
Quoted 4 lines
common/usb_kbd.c +4 -0
+		return 0;
+	else
+		kbd_testc_tms = get_timer(0);
+#endif
I have a hard time understanding why the fact that "some other task is running" implies anything at all re: how often usb_kbd_testc() would be called.
Quoted 6 lines
In my case it takes about 95 ms on Tegra20 and Tegra114 for usb_kbd_testc() to be called periodically.
So I set CONFIG_USBKB_TESTC_PERIOD to 100.
Like I said, if CONFIG_USBKB_TESTC_PERIOD ms < T < 1000 ms we reduce polling (send command to USB keyboard to check is there any key pressed) to every second.
OK, so I think how this works is: If nothing is happening, then usb_kbd_testc() is repeatedly called back-to-back with no delay between. So, if the time between two calls to usb_kbd_testc() is much longer than the time it takes to execute it once, then something else is going on, and hence the code should skip some calls to usb_kbd_testc().

Quoted 5 lines

If that's how this works, then why require CONFIG_USBKBD_TESTC_PERIOD to be set? Why not simply measure the time between when usb_kbd_testc() returns, and when it is re-entered? If it's very short, nothing else is happening. If it's very long, something else is happening. That is a far more direct measurement, and is immune to e.g. CPU frequency differences

Good idea and will be introduced in next revision.

Quoted 8 lines

in a way that a static value for CONFIG_USBKBD_TESTC_PERIOD is not.
Also, any kind of time measurement doesn't solve the issue I mentioned
re: how granular the other task is.
Finally, if you're sitting at the command-prompt, is usb_kbd_testc() used at all? How does regular typing using a USB keyboard interact with this code; will typing react fast, but CTRL-C react slowly?

They should react at same rate.

--
nvpublic