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Posts: 58 | Thanked: 8 times | Joined on Aug 2010
#1
Hi, when I compile the kernel of N900(2.6.28-omap1) for the first time in scratchbox, the time is quite long, everyone knows that. And then I made some change of the kernel, recompile it, now the compile time becomes short.

But if I quit scratchbox and re-login it again, and re-compile the kernel, the time is as long as the first time I do it. Does anyone know why? And how to solve this problem?
Thanks!
 
Posts: 274 | Thanked: 82 times | Joined on Dec 2009
#2
Get a faster computer?
 
Posts: 96 | Thanked: 105 times | Joined on Aug 2006 @ Finland
#3
Maybe some timestamp won't match anymore after logout/login. Use verbose build to se what it's doing.
Maybe even try ccache if that might help recompiles.
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Posts: 2,802 | Thanked: 4,491 times | Joined on Nov 2007
#4
Ccache is installed and used by default, that's why the second compilation is much faster. I've no idea why logging out of scratchbox makes it longer for the OP though.
 

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Posts: 549 | Thanked: 299 times | Joined on Jun 2010 @ Australian in the Philippines
#5
Do you have a bunch of spare cores in your CPU? I tend to increase the number of jobs to run in parallel based on the number of CPU's and cores I have. Eg.

make -j 4 bzImage

This should speed things along a tad assuming you have a quad core machine, though you can vary the number up or down depending.
 
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Posts: 302 | Thanked: 193 times | Joined on Oct 2008 @ England
#6
If it's the same as Gentoo then it's -j total number of cores + 1
 
Posts: 58 | Thanked: 8 times | Joined on Aug 2010
#7
Originally Posted by teh View Post
Get a faster computer?
Yes, that is a good way and I have done that.
 
Posts: 58 | Thanked: 8 times | Joined on Aug 2010
#8
Originally Posted by dchky View Post
Do you have a bunch of spare cores in your CPU? I tend to increase the number of jobs to run in parallel based on the number of CPU's and cores I have. Eg.

make -j 4 bzImage

This should speed things along a tad assuming you have a quad core machine, though you can vary the number up or down depending.
This is a good suggestion, I will try it.
 
Posts: 58 | Thanked: 8 times | Joined on Aug 2010
#9
Originally Posted by onion View Post
Maybe some timestamp won't match anymore after logout/login. Use verbose build to se what it's doing.
Maybe even try ccache if that might help recompiles.
I think your answer is most reasonable. Unfortunately I cannot repeat what I mentioned. Now whenever I recompile the kernel under scratchbox(in any case), the compile time is short. I don't know why.
 
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Posts: 549 | Thanked: 299 times | Joined on Jun 2010 @ Australian in the Philippines
#10
Originally Posted by Captwheeto View Post
If it's the same as Gentoo then it's -j total number of cores + 1
No, it's just -j <Total Number of Cores> only. Not plus 1 :-) You wont see any improvement unfortunately. +2 or more above the number of cores and you're more likely to have compile times take (sometimes significantly) longer.
 
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