Linux Kernel/Boot Time - Revision history

Dvhart: /* Vision */

2011-06-23T21:32:03Z

Vision

← Older revision		Revision as of 21:32, 23 June 2011
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	== Vision ==		== Vision ==
	Provide an example layer which demonstrates how to minimize the boot-time of the Intel N-450 Development platform. Publish a document on how to apply the techniques used in the demonstration layer to an arbitrary BSP. Using a core-image-minimal image (or a customized version of it), boot to a login prompt in 2.0 seconds.		Provide an example layer which demonstrates how to minimize the boot-time of the Intel N-450 Development platform. Publish a document on how to apply the techniques used in the demonstration layer to an arbitrary BSP. Using a core-image-minimal image (or a customized version of it), boot to a login prompt in 2.0 seconds. Try to stick with configuration options and upstreamable patches as far as is possible. Further reduction in boot-time can be had with BSP specific hacks and hard-coding of certain initialization routines, but they should be a last resort as they are expensive to maintain.

	== Design ==		== Design ==

Dvhart: /* Vision */

2011-06-23T18:30:28Z

Vision

← Older revision		Revision as of 18:30, 23 June 2011
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	== Vision ==		== Vision ==
	Provide an example layer which demonstrates how to minimize the boot-time of the Intel N-450 Development platform. Using a core-image-minimal image (or a customized version of it), boot to a login prompt in 2.0 seconds.		Provide an example layer which demonstrates how to minimize the boot-time of the Intel N-450 Development platform. Publish a document on how to apply the techniques used in the demonstration layer to an arbitrary BSP. Using a core-image-minimal image (or a customized version of it), boot to a login prompt in 2.0 seconds.

	== Design ==		== Design ==

Dvhart: /* Vision */

2011-06-23T18:29:24Z

Vision

← Older revision		Revision as of 18:29, 23 June 2011
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	== Vision ==		== Vision ==
	Provide an example layer which demonstrates how to minimize the boot-time of the Intel N-450 Development platform. Using a core-image-minimal image, boot to a login prompt in 2.0 seconds.		Provide an example layer which demonstrates how to minimize the boot-time of the Intel N-450 Development platform. Using a core-image-minimal image (or a customized version of it), boot to a login prompt in 2.0 seconds.

	== Design ==		== Design ==

Dvhart: /* Design */

2011-06-23T18:28:47Z

Design

← Older revision		Revision as of 18:28, 23 June 2011
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	== Design ==		== Design ==
	The current linux-yocto kernel configuration does not focus on minimal boot time. Eliminating unnecessary Linux kernel config options will reduce the image size as well as the boot time. Various boot parameters can also have a significant impact. Identify specific items through exploration of:		The current linux-yocto kernel configuration does not focus on minimal boot time. Eliminating unnecessary Linux kernel config options will reduce the image size as well as the boot time. All drivers required for boot shall be built-in to the kernel, those needed after boot for applications or likely use cases can be relegated to modules. Various boot parameters can also have a significant impact. Identify specific items through exploration of:

	* linux/scripts/bootgraph.pl		* linux/scripts/bootgraph.pl

Dvhart: /* Design */

2011-06-23T18:27:30Z

Design

← Older revision		Revision as of 18:27, 23 June 2011
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	The boot process should look like the following:		The boot process should look like the following:
			<pre>
	BIOS -> Loader -> Kernel -> Userspace -> basic init -> start apps -> module load		BIOS -> Loader -> Kernel -> Userspace -> basic init -> start apps -> module load
			</pre>

Dvhart at 18:27, 23 June 2011

2011-06-23T18:27:09Z

← Older revision		Revision as of 18:27, 23 June 2011
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	== Design ==		== Design ==
	The current linux-yocto kernel configuration does not focus on minimal boot time. Eliminating ~~necessary~~ Linux kernel config options will reduce the image size as well as the boot time. Various boot parameters can also have a significant impact. Identify specific items through exploration of:		The current linux-yocto kernel configuration does not focus on minimal boot time. Eliminating unnecessary Linux kernel config options will reduce the image size as well as the boot time. Various boot parameters can also have a significant impact. Identify specific items through exploration of:

	* linux/scripts/bootgraph.pl		* linux/scripts/bootgraph.pl
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	* survey of talks and papers on the subject		* survey of talks and papers on the subject
	* research coreboot and other BIOS replacements for the N450		* research coreboot and other BIOS replacements for the N450

			The boot process should look like the following:
			BIOS -> Loader -> Kernel -> Userspace -> basic init -> start apps -> module load


	The boot-time budget follows:		The boot-time budget follows:
	* BIOS: 0.5s		* BIOS: 0.5s
			** Assuming a BLDK or other custom fast-boot BIOS
	* Kernel + Modules: 1s		* Kernel + Modules: 1s
	* Init to prompt: 0.5s		* Init to prompt: 0.5s
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	* serial8250* (0.4s)		* serial8250* (0.4s)
	* Current total: 2.6s (2.2s without async_port)		* Current total: 2.6s (2.2s without async_port)
			* Possibly M3 work
			** udev audit
			** hardcode required /dev/* nodes
			** remove unnecessary configurations from udev (SCSI, IB, etc.)
			** start udev early, but delay the event handler and settling until after boot

	== Resources ==		== Resources ==

Dvhart at 21:13, 22 June 2011

2011-06-22T21:13:01Z

← Older revision		Revision as of 21:13, 22 June 2011
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	* http://elinux.org/Boot_Time		* http://elinux.org/Boot_Time

	== Bootgraph Results ==		== Journal ==
	=== Initial State: 2.6.34 (UP), USB ===		=== Bootgraph Results ===
			==== Initial State: 2.6.34 (UP), USB ====
	[[File:n450-2.6.34-usb.png\|400px\|thumb\|right]]		[[File:n450-2.6.34-usb.png\|400px\|thumb\|right]]
	* Yocto 1.0		* Yocto 1.0
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	<br style="clear:both" />		<br style="clear:both" />

	=== 2.6.34 (SMT), SSD ===		==== 2.6.34 (SMT), SSD ====
	[[File:n450-2.6.34-smt-ssd.png\|400px\|thumb\|right]]		[[File:n450-2.6.34-smt-ssd.png\|400px\|thumb\|right]]
	* Yocto 1.0		* Yocto 1.0
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	<br style="clear:both" />		<br style="clear:both" />

	=== 2.6.34 (SMT), SSD, NOKMS ===		==== 2.6.34 (SMT), SSD, NOKMS ====
	[[File:n450-2.6.34-smt-ssd-nokms.png\|400px\|thumb\|right]]		[[File:n450-2.6.34-smt-ssd-nokms.png\|400px\|thumb\|right]]
	* Yocto 1.0		* Yocto 1.0
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	<br style="clear:both" />		<br style="clear:both" />

	=== 2.6.37 (SMT), SSD, NOKMS ===		==== 2.6.37 (SMT), SSD, NOKMS ====
	[[File:n450-2.6.37-ssd-nokms-serial.png\|400px\|thumb\|right]]		[[File:n450-2.6.37-ssd-nokms-serial.png\|400px\|thumb\|right]]
	* Yocto 1.0+		* Yocto 1.0+
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	<br style="clear:both" />		<br style="clear:both" />

	=== 2.6.37 (SMT), SSD, NOKMS, No Serial ===		==== 2.6.37 (SMT), SSD, NOKMS, No Serial ====
	[[File:n450-2.6.37-ssd-nokms.png\|400px\|thumb\|right]]		[[File:n450-2.6.37-ssd-nokms.png\|400px\|thumb\|right]]
	* Yocto 1.0+		* Yocto 1.0+

Dvhart: /* Resources */

2011-06-22T18:40:02Z

Resources

← Older revision		Revision as of 18:40, 22 June 2011
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	* [http://git.kernel.org/?p=linux/kernel/git/dvhart/yocto/meta-boottime.git;a=summary Boot Time Layer]		* [http://git.kernel.org/?p=linux/kernel/git/dvhart/yocto/meta-boottime.git;a=summary Boot Time Layer]
	* [http://www.slideshare.net/andrewmurraympc/elce-the ELC 2010: The Right Approach to Minimal Boot Times]		* [http://www.slideshare.net/andrewmurraympc/elce-the ELC 2010: The Right Approach to Minimal Boot Times]
			* http://elinux.org/Boot_Time

	== Bootgraph Results ==		== Bootgraph Results ==

Dvhart at 17:45, 14 June 2011

2011-06-14T17:45:52Z

← Older revision		Revision as of 17:45, 14 June 2011
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	* Kernel + Modules: 1s		* Kernel + Modules: 1s
	* Init to prompt: 0.5s		* Init to prompt: 0.5s

			== Next Steps ==
			* what runs before start @ 0.38s
			* e100_init_module (0.4s)
			* [23]_async_port_probe (0.8s-1.3s)
			* alsa_card_azx_init (0.4s)
			* serial8250* (0.4s)
			* Current total: 2.6s (2.2s without async_port)

	== Resources ==		== Resources ==

Dvhart at 17:43, 14 June 2011

2011-06-14T17:43:06Z

← Older revision		Revision as of 17:43, 14 June 2011
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	** Some 15 seconds is due to the default BIOS		** Some 15 seconds is due to the default BIOS
	* Bootgraph logged 12s		* Bootgraph logged 12s
			<br style="clear:both" />

	=== 2.6.34 (SMT), SSD ===		=== 2.6.34 (SMT), SSD ===
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	* Bootgraph logged 6.32s		* Bootgraph logged 6.32s
	** SSD saves some 6 seconds		** SSD saves some 6 seconds
			<br style="clear:both" />

	=== 2.6.34 (SMT), SSD, NOKMS ===		=== 2.6.34 (SMT), SSD, NOKMS ===
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	* Bootgraph logged 3.98s		* Bootgraph logged 3.98s
	** NOKMS saves some 2.36s		** NOKMS saves some 2.36s
			<br style="clear:both" />

	=== 2.6.37 (SMT), SSD, NOKMS ===		=== 2.6.37 (SMT), SSD, NOKMS ===
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	* Boot parameters: i915.modeset=0		* Boot parameters: i915.modeset=0
	* Bootgraph logged 4.05s		* Bootgraph logged 4.05s
			<br style="clear:both" />

	=== 2.6.37 (SMT), SSD, NOKMS, No Serial ===		=== 2.6.37 (SMT), SSD, NOKMS, No Serial ===
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	* Bootgraph logged 2.39s		* Bootgraph logged 2.39s
	** no serial saves 1.66s		** no serial saves 1.66s
			<br style="clear:both" />

	== Notes ==		== Notes ==