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Old 01-06-2009, 03:14 PM
Scott James Remnant
 
Default Intrepid vs. Jaunty kernels (monolithic vs. built-in)

It's also worth comparing the Intrepid and Jaunty kernels in general.
This has some key figures because we're switching to more modules
built-in than before.

To try and split the difference, I built two "jaunty" kernels: 2.6.28-3
is from GIT just before the configs were changed; 2.6.28-4 is current
GIT HEAD.

This isn't 100% fair, since other changes have happened between the
kernels, but it's close as feel like getting


Bear in mind that 2.6.28-4 also includes the change to reduce the legacy
pty count to zero, so that will affect various numbers.


Average processing times between kernel uevent and udev completion:

2.6.27-9 2.6.28-3 2.6.28-4
MEAN 6.88s 7.81s 5.01s
MEDIAN 8.07s 8.87s 5.55s
MODE 8.13s 2.80s 5.28s
STDDEV 2.44s 2.67s 2.95s


Interesting that 2.6.28 seems to take rather longer, with a much reduced
mode (most common figure), and that 2.6.28-4 undoes that to make it
generally faster again.

Numbers are comparable to the legacy pty change, which isn't totally
surprising really - the behemoth of module pain (ALSA) is still a
module.


General instrumenting:

2.6.27-9 2.6.28-3 change 2.6.28-4 change total change
udev in initramfs: 0.01s 0.02s +0.01s (200%) 0.01s -0.01s (50%) 0 (100%)
udev in system: 0.05s 0.04s -0.01s (80%) 0.04s 0 (100%) -0.01s (80%)

trigger in initramfs: 0.29s 0.22s -0.07s (75%) 0.09s -0.13s (40%) -0.20s (31%)
trigger in system: 0.60s 0.24s -0.36s (40%) 0.16s -0.08s (66%) -0.44s (26%)

processing in initramfs: 2.58s 3.82s +1.24s (148%) 2.25s -1.57s (58%) -0.33s (87%)
processing in system: 10.45s 11.86s +1.41s (113%) 9.37s -2.49s (79%) -1.08s (89%)

time in kernel: 2.61s 2.61s 0 (100%) 2.63s +0.02s (100%) +0.02s (100%)
time in initramfs: 3.59s 4.56s +0.97s (127%) 2.96s -1.60s (64%) -0.63s (82%)
(of which udev) 71% 83% 76%
time booting system: 25.65s 26.45s +0.80s (103%) 21.54s -4.91s (81%) -4.11s (83%)
(of which udev) 40% 44% 43%

Again we see that 2.6.28 takes longer than 2.6.27, not just in the
system (which we could blame on readahead) but in initramfs as well.
More to do, maybe?

We then see that more things as built-ins certainly reduces lots of
overhead. The udevadm settle in initramfs drops by a third of a second,
and the one in the main system by over a seccond.

In total, the system comes up almost five seconds quicker.

What's really interesting here is that the time in kernel doesn't seem
to change at all - even with the built-ins, the initramfs starts at
basically the same clock time.


Scott
--
Scott James Remnant
scott@canonical.com
--
kernel-team mailing list
kernel-team@lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/kernel-team
 
Old 01-06-2009, 05:37 PM
Jim Lieb
 
Default Intrepid vs. Jaunty kernels (monolithic vs. built-in)

To put some perspective on this I timed boot of Intrepid (Kubuntu) and
Vista on the same HP Pavilion dv7 (Turion64x2 + 4GB +sata 320G).
Times are stopwatch, YMMV.

<CR> to grub to login prompt (kdm/windows login):
Kubuntu 2.6.27-10: 44.4 sec
Vista 46.3 sec

<CR> after entering password to usable desktop:
Kubuntu 24 sec
Vista 18 sec

Both desktops continued to do things like update rss feed stuff and
restore desktop (open firefox) so the login number is a bit mushy;
basically, when the busy cursor stopped going around (much).

Both had longer boot times when either fsck had to run or Vista needed
to finish update installs. Add 1-2 mins...

Two things come to mind.

1. There is a reason why shutdown/restart is on a secondary menu w/
suspend being the button for Vista.

2. I don't have to be faster than the bear, only faster than you.

We should wring out the wasted time (lots of it) but keep perspective,
i.e. initramfs is a good thing and modules make config life easier/better.
*And* getting suspend/resume to work every time is the real win.

Jim

On Tuesday 06 January 2009 08:14:39 Scott James Remnant wrote:
> It's also worth comparing the Intrepid and Jaunty kernels in general.
> This has some key figures because we're switching to more modules
> built-in than before.
>
> To try and split the difference, I built two "jaunty" kernels: 2.6.28-3
> is from GIT just before the configs were changed; 2.6.28-4 is current
> GIT HEAD.
>
> This isn't 100% fair, since other changes have happened between the
> kernels, but it's close as feel like getting
>
>
> Bear in mind that 2.6.28-4 also includes the change to reduce the legacy
> pty count to zero, so that will affect various numbers.
>
>
> Average processing times between kernel uevent and udev completion:
>
> 2.6.27-9 2.6.28-3 2.6.28-4
> MEAN 6.88s 7.81s 5.01s
> MEDIAN 8.07s 8.87s 5.55s
> MODE 8.13s 2.80s 5.28s
> STDDEV 2.44s 2.67s 2.95s
>
>
> Interesting that 2.6.28 seems to take rather longer, with a much reduced
> mode (most common figure), and that 2.6.28-4 undoes that to make it
> generally faster again.
>
> Numbers are comparable to the legacy pty change, which isn't totally
> surprising really - the behemoth of module pain (ALSA) is still a
> module.
>
>
> General instrumenting:
>
> 2.6.27-9 2.6.28-3 change 2.6.28-4 change total change
> udev in initramfs: 0.01s 0.02s +0.01s (200%) 0.01s -0.01s (50%) 0
> (100%) udev in system: 0.05s 0.04s -0.01s (80%) 0.04s 0
> (100%) -0.01s (80%)
>
> trigger in initramfs: 0.29s 0.22s -0.07s (75%) 0.09s -0.13s
> (40%) -0.20s (31%) trigger in system: 0.60s 0.24s -0.36s (40%)
> 0.16s -0.08s (66%) -0.44s (26%)
>
> processing in initramfs: 2.58s 3.82s +1.24s (148%) 2.25s -1.57s
> (58%) -0.33s (87%) processing in system: 10.45s 11.86s +1.41s (113%)
> 9.37s -2.49s (79%) -1.08s (89%)
>
> time in kernel: 2.61s 2.61s 0 (100%) 2.63s +0.02s (100%)
+0.02s
> (100%) time in initramfs: 3.59s 4.56s +0.97s (127%) 2.96s -1.60s
> (64%) -0.63s (82%) (of which udev) 71% 83% 76%
> time booting system: 25.65s 26.45s +0.80s (103%) 21.54s -4.91s
> (81%) -4.11s (83%) (of which udev) 40% 44% 43%
>
> Again we see that 2.6.28 takes longer than 2.6.27, not just in the
> system (which we could blame on readahead) but in initramfs as well.
> More to do, maybe?
>
> We then see that more things as built-ins certainly reduces lots of
> overhead. The udevadm settle in initramfs drops by a third of a second,
> and the one in the main system by over a seccond.
>
> In total, the system comes up almost five seconds quicker.
>
> What's really interesting here is that the time in kernel doesn't seem
> to change at all - even with the built-ins, the initramfs starts at
> basically the same clock time.
>
>
> Scott

--
Jim Lieb
Ubuntu Kernel Team
Canonical Ltd.

--
kernel-team mailing list
kernel-team@lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/kernel-team
 

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