Interesting observation: 2x2.0Ghz -vs- 450Mhz machine

W

wlohman

I still have my first laptop. It came with W98 at the time, and was specced like this: 450Mhz AMD, 32MB RAM and a 4GB HD. I added 128MB RAM later. This machine was never liked by Linux, but FreeBSD 7.0 felt right at home on the device.

My day to day machine is also a laptop, 2x2.0Ghz (Core2Duo), 1GB RAM and 80GB HD. This one has been running Slackware for years, but it now has FreeBSD 7.2 installed.

Both where build with the X-user profile from the install CD.

Set side by side, if I don't take BIOS into account, the 450Mhz machine reaches textual login a good 10 seconds faster than the 2x2.0Ghz machine. 31 seconds and 42 seconds respectively.

This is not a question. It's just, I can't get my mind around how something that should be eight times slower is actually noticeably faster in terms of boot time.
Obviously once both devices are fully booted, the new machine is much much faster.
 
Doesn't the newer machine have lots more hardware that needs to be probed and recognised? Is there a big difference between [cmd=] dmesg -a | wc -l[/cmd] on both machines?
 
DutchDaemon said:
Doesn't the newer machine have lots more hardware that needs to be probed and recognised? Is there a big difference between [cmd=] dmesg -a | wc -l[/cmd] on both machines?
Click to expand...

174 and 311 respectively, after a reboot.

Would that explain it? I know probing hardware takes time, perhaps more time than can be gotten back with CPU power? Because my thought was that the kernel probes the hardware in the early stage of the boot process. I'm not familiar enough with BSD to see exactly where during boot the kernel finishes loading and hands over control to init; where we reach filesystem level and I'd expect CPU power and a fast diskdrive to kick in and make a difference.


But observing the 450Mhz machine closely leads me to believe this point indeed is reached later in the process than I thought (and thus, hypothetically, doesn't do much to make up for the time it takes to probe).


Am I right to think that the moment the sequence displays the message: "Trying to mount root on blah" is the moment the kernel hands over control to init? Because that is indeed for my new machine relatively near the end of the sequence. And it would explain my observation :e
 
init kicks in just slightly after that, I believe (it makes sure the disks are in a usable state before actually mounting them, so "Starting file system checks" should indicate init taking over). Not entirely sure.
 
My laptop has a nice, long pause while it probes the card-reader for its ostensibly enumerated /dev/da0. Also, I think that probing the possible sata devices adds a bit, since both machines will have the [p]ata bus probed in about the same time.

Then there's all the usb devices (I think I have 6 controllers in this machine, which seems a bit absurd).
 
wlohman said:
I still have my first laptop. It came with W98 at the time, and was specced like this: 450Mhz AMD, 32MB RAM and a 4GB HD. I added 128MB RAM later. This machine was never liked by Linux, but FreeBSD 7.0 felt right at home on the device.

My day to day machine is also a laptop, 2x2.0Ghz (Core2Duo), 1GB RAM and 80GB HD. This one has been running Slackware for years, but it now has FreeBSD 7.2 installed.

Both where build with the X-user profile from the install CD.

Set side by side, if I don't take BIOS into account, the 450Mhz machine reaches textual login a good 10 seconds faster than the 2x2.0Ghz machine. 31 seconds and 42 seconds respectively.

This is not a question. It's just, I can't get my mind around how something that should be eight times slower is actually noticeably faster in terms of boot time.
Obviously once both devices are fully booted, the new machine is much much faster.
Click to expand...

My second machine I purchased in my lifetime was a custom built machine I put together.

-AMD Athlon 650 Mhz Slot A
-Asus K7V System Board
-1.5 GB SDRAM
-2 x 150 GB WD Drives in RAID1 with a Promise Technology SCSI Raid Controller
-2 x D-link 10/100 network cards
-Sound Blaster Live audio card
-VOODOO 3 graphics card
-2x CD Burner/Reader

My old machine is still running as if it were new. I just replaced the PSU with a new Enermax 450 Watt PSU, replaced the tower/case, & purchased a dvd reader. All the upgrades ran me about $100 CAD with taxes.

My 6 year old niece and 5 year old nephew now have their own computer they now use to learn various things I teach them on their computer.

Its running a custom compiled Linux 2.6.31 kernel. Its screaming fast. I wish someone had introduced me to Linux or Unix when I was 5 years old :)
 
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