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Apopatos
Guru
Joined: 17 Oct 2004
Posts: 512
Location: Hellas
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 Posted: Sun Nov 22, 2009 2:38 pm Post subject: GZIP and boot performance... |
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Hi guys,
I'm trying to reduce my boot time to minimum and I'm experimenting with a lot of things.
Frist of all I removed a lot of unnecessary things from kernel, reduced the use of modules to minimum, used wicd for networking setup, enabled parallel process and used an fbsplash theme with jpg images instead of png. I'm thinking to use runit or something similar instead of init as well but as far as I have seen they don't support fbsplash... anyway
The things go nice so far. With my 5 years old Athlon64 3000+ I have boot time 22 seconds from lilo to KDM but the weird thing is this one:
I read somewhere that if you have a fast CPU and slow I/O as it happens in x86, is possible bzip2 to decompress faster than gzip. I found this very odd but I decided to give it a try, it's free afterall 
So, I tried all three kernel compressions. Gzip, Bzip2 and LZMA.
Results:
GZIP 20 secs for kernel initialization --> 30 secs from lilo to kdm 
Bzip2 13 secs for kernel initialization --> 23 secs from lilo to kdm
LZMA 12 secs for kernel initialization --> 22 secs from lilo to kdm
So I stick with lzma for now. But isn't odd for gzip to take soooo long? Over 50% slower than Bzip2  |
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wswartzendruber
Veteran
Joined: 23 Mar 2004
Posts: 1261
Location: Idaho, USA
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| Posted: Sun Nov 22, 2009 3:08 pm Post subject: |
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That's weird. LZMA takes at least twice as long on my Core 2 machine.
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Apopatos
Guru
Joined: 17 Oct 2004
Posts: 512
Location: Hellas
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| Posted: Sun Nov 22, 2009 5:21 pm Post subject: |
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| wswartzendruber wrote: | | That's weird. LZMA takes at least twice as long on my Core 2 machine. |
That's the normal.
How long takes your kernel initialization? |
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Apopatos
Guru
Joined: 17 Oct 2004
Posts: 512
Location: Hellas
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| Posted: Mon Nov 23, 2009 11:25 am Post subject: |
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| I wonder btw wh there is not an option for uncompressed kernel. It would help so much the boot time. |
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Hupf
Tux's lil' helper
Joined: 11 Sep 2005
Posts: 112
Location: Germany
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| Posted: Mon Nov 23, 2009 4:52 pm Post subject: |
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| Apopatos wrote: | | I wonder btw wh there is not an option for uncompressed kernel. It would help so much the boot time. |
Most laptops today have a decent processor, but a very slow hard disk. For me, bootchart shows that the CPU is idling most of the time and that the HDD is always under load. The logical step here is compression: move some load away from the current bottleneck which is the harddisk.
YMMV, esp. on desktops with fast HDD or even RAID and on systems with slow processors (e.g. Celeron-III 333MHz). |
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