Re: New fast(?)-boot results on ARM

[Dirk Behme <dirk.behme@googlemail.com>]

Sascha Hauer wrote:
> On Tue, Aug 18, 2009 at 05:31:42PM +0200, Dirk Behme wrote:
>> Sascha Hauer wrote:
>>> On Fri, Aug 14, 2009 at 07:02:28PM +0200, Robert Schwebel wrote:
>>>> Hi,
>>>>
>>>> On Thu, Aug 13, 2009 at 05:33:26PM +0200, Robert Schwebel wrote:
>>>>> On Thu, Aug 13, 2009 at 08:28:26AM -0700, Arjan van de Ven wrote:
>>>>>>> That's bad :-) So there is no room for improvement any more in our
>>>>>>> ARM boot sequences ...
>>>>>> on x86 we're doing pretty well ;-)
>>>>> On i.MX27 (400 MHz ARM926EJ-S) we currently need 7 s, measured from
>>>>> power-on through the kernel up to "starting init". This is with
>>>>>
>>>>> - no delay in u-boot-v2
>>>>> - rootfs on NAND (UBIFS)
>>>>> - quiet
>>>>> - precalculated loops-per-jiffy
>>>>> - zImage kernel instead of uImage
>>>> Here's a little video of our demo system booting:
>>>> http://www.youtube.com/watch?v=xDbUnNsj0cI
>>>>
>>>> As you can see there, it needs about 15 s from the release of the reset button
>>>> up to the moment where the application shows it's Qt 4.5.2 based GUI (which is
>>>> when we fade over from the initial framebuffer to the final one, in order to
>>>> hide the qt application startup noise).
>>>>
>>>> And below is the boot log (after turning "quiet" off again). The numbers are
>>>> the timestamp and the delta to the last timestamp, measured on the controlling
>>>> PC by looking at the serial console output. The ptx_ts script starts when the
>>>> regexp was found, so the numbers start basically in the moment when u-boot-v2
>>>> has initialized the system up to the point where we can see something.
>>>>
>>>> Result:
>>>>
>>>> - 2.4 s up from u-boot to the end of "Uncompressing Linux"
>>>> - 300 ms until ubifs initialization starts
>>>> - 3.7 s for ubifs, until "mounted root"
>>>>
>>>> So we basically have 7 s for the kernel. The rest is userspace, which hasn't
>>>> seen much optimization yet, other than trying to start the GUI application as
>>>> early as possible, while doing all other init stuff in parallel. Adding "quiet"
>>>> brings us another 300 ms.
>>>>
>>>> That's factor 70 away from the 110 ms boot time Tim has talked about some days
>>>> ago (and he measured on an ARM cpu which had almost half the speed of this
>>>> one), and I'm wondering what we can do to improve the boot time.
>>>>
>>>> Robert
>>>>
>>>> rsc@thebe:~$ microcom | ptx_ts "U-Boot 2.0.0-rc9"
>>>> [ 13.522625] <  0.043189>
>>>> [ 13.546627] <  0.024002> OSELAS(R)-phyCORE-trunk (PTXdist-1.99.svn/2009-08-06T08:37:25+0200)
>>>> [ 13.558613] <  0.011986>
>>>> [ 13.690643] <  0.132030>        _            ____ ___  ____  _____
>>>> [ 13.690731] <  0.000088>  _ __ | |__  _   _ / ___/ _ \|  _ \| ____|
>>>> [ 13.698595] <  0.007864> | '_ \| '_ \| | | | |  | | | | |_) |  _|
>>>> [ 13.698654] <  0.000059> | |_) | | | | |_| | |__| |_| |  _ <| |___
>>>> [ 13.702581] <  0.003927> | .__/|_| |_|\__, |\____\___/|_| \_\_____|
>>>> [ 13.706573] <  0.003992> |_|          |___/
>>>> [ 13.706622] <  0.000049>
>>>> [ 13.725043] <  0.018421>
>>>> [ 14.742608] <  1.017565>
>>> I made some changes suggested in this thread:
>>>
>>> - enable MMU in the bootloader
>>> - use assembler optimized memcpy/memset in the bootloader
>>> - start an uncompressed image
>>> - disable IP autoconfiguration in the Kernel
>>> - use lpj= command line parameter
>>> - use static device nodes instead of udev
>>> - skip some init scripts
>>> - made the kernel smaller (I do not have both configs handy, so I do not
>>>   know what exactly I changed)
>>>
>>> Already looks much better:
>>>
>>> [  0.000005] <  0.000005> U-Boot 2.0.0-rc10-00241-g3f10fe9-dirty (Aug 18 2009 - 13:29:25)
>>> [  0.000026] <  0.000021>
>>> [  0.000041] <  0.000015> Board: Phytec phyCORE-i.MX27
>>> [  0.000054] <  0.000013> cfi_probe: cfi_flash base: 0xc0000000 size: 0x02000000
>>> [  0.000067] <  0.000013> NAND device: Manufacturer ID: 0x20, Chip ID: 0x36 (ST Micro NAND 64MiB 1,8V 8-bit)
>>> [  0.000080] <  0.000013> imxfb@imxfb0: i.MX Framebuffer driver
>>> [  0.000092] <  0.000012> dma_alloc: 0xa6f56e40 0x10000000
>>> [  0.000105] <  0.000013> dma_alloc: 0xa6f57088 0x10000000
>>> [  0.000118] <  0.000013> dev_protect: currently broken
>>> [  0.000129] <  0.000011> Using environment in NOR Flash
>>> [  0.000141] <  0.000012> initialising PLLs
>>> [  0.128972] <  0.128831> Malloc space: 0xa6f00000 -> 0xa7f00000 (size 16 MB)
>>> [  0.128995] <  0.000023> Stack space : 0xa6ef8000 -> 0xa6f00000 (size 32 kB)
>>> [  0.129008] <  0.000013> running /env/bin/init...
>>> [  0.224963] <  0.095955>
>>> [  0.224984] <  0.000021> Hit any key to stop autoboot:  0
>>> [  0.224999] <  0.000015> copy
>>> [  0.592964] <  0.367965> done
>>> [  0.652010] <  0.059046> Linux version 2.6.31-rc4-00004-g05786f8-dirty (sha@octopus) (gcc version 4.3.2 (OSELAS.Toolchain-1.99.3) ) #206 PREEMPT Tue Aug 18 14:08:51 CEST 2009
>> So, this are ~0.6 s in boot loader and kernel copy until kernel starts, 
>> correct?
> 
> Yes, correct. The copying itself is between 'copy' and 'done' so it
> takes about 0.4s.
> 
>> What's the size of the uncompressed kernel copied here?
> 
> The image is about 2.8MB, but I copied the whole partition of 3MB
> because with raw images you can't detect the image size.

With 3MB copied in ~0.4s you get ~8MB/s. This really depends on your 
HW, but I would think with standard NOR flashes you should be able to 
do at least two (three?) times better. Have you already checked the 
memory (NOR flash) timings configured in your SoC?

See the second topic of

http://elinux.org/Boot_Time#Boot_time_check_list

too ;)

Best regards

Dirk