I'm currently waiting for the second pass of gcc to finish its make. As the other packages left have less SBU's I'd like to run a parelle make but am a bit confused on whether it is possible with a Pentium 4 HT as there are two logical CPUs but essentially its just a single core.

Is there any way to check this out?

Check the output of the following command:If more then one processor is mentioned you can use export MAKEFLAGS='-j 2' or make -j2

One thing I should mention about using parallel make: Not all packages like this option, if a make (or make check) fails with the following message try removing the -j2 part and rerun the command.

Message pointing to possible -j2 conflict: BTW: Do not use a number greater then the amount of cpu's (example: if you have 2 cpu's/cores, do _not_ use -j3)

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It depends: If you have a fast storage subsystem there is no problem with using higher numbers. I do all my compiles on a tmpfs in RAM and I can easily run my compiles with -j10 on my 6-core machine. On a machine with Hyperthreading, especially in its older versions (like the OP's Pentium 4) this is of course not really advisable.

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@TobiSGD: Definitely a truism

I was giving advise with the Pentium 4 HT in mind and the recollection of an earlier thread that came across this issue (the build failing miserably).

We could start a general discussion about the actual added value of assigning more core's/cpu's then actually present, but i'm sure this is not the place to do so

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I do not think it depends on that. Just try -j2, -j3 or even more, and look at the speed. And yes, try to use tmpfs.

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[QUOTE=druuna;4929697]Check the output of the following command:If more then one processor is mentioned you can use export MAKEFLAGS='-j 2' or make -j2

{/QUOTE]

A really dumb question here, but what field shows the number of processors? Mine doesn't show any, so I assume its just a single processor?

I have a result like this (of cat /proc/cpuinfo):
processor: 0
vendor_id ....
....

processor: 1
vendor ...
...

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Thank you.
Mine only gives info for processor: 0, which I take as meaning its just single core.

Adding to the discussion built up earlier, is it recommended if I use make -j2 ?

If you only have one core I wouldn't use the -j2 flag.

The above is with your hardware in mind, although I do think there isn't a point in doing so even if you would have a fast machine (fast storage subsystem / tmpfs in RAM / etc).

I haven't actually tested this but I do believe both threads are being handled by one core (assuming one core cpu and -j2) and this will not increase the build speed. I wouldn't be surprised if it will be slightly (??) slower when using -j2 compared to -j1 (or no -j flag).

from my point of view you would need to check it, probably helps.

I just did a little searching and came up with 3 conflicting "rules":

1) amount of cores dictates the -j number (2 cores => -j2),
2) use 1.5 times the amount of cores (2 cores => -j3),
3) use 2 times the amount of cores (2 cores => -j4).

The GNU make page (this one) doesn't help.

I have to agree with pan64: You need to do some testing to figure out what is fastest/best for your scenario.

EDIT: Just quick tested the above rules using binutils and this is the result (I'm having an 8 core cpu):

make -j1 -> real 2m0.806s
make -j8 -> real 0m31.561s
make -j12 -> real 0m31.790s
make -j16 -> real 0m32.232s

Well, considering as I have just around four more to go to complete Chapter 5 and they have low SBU values, will just give it a try, for better or for worse.

After searching a bit, I'm a bit confused on how to use tmpfs on RAM. What would be a suitable material to refer?

Thank You!

Sorry druuna, I didn't see your reply. This seems very interesting and promising. I'll do some checking and be back.

BTW adding a typical newbie question: would it be a problem if I run binutils or gcc again to test this? Because I guess its no point of running it for lesser SBU values.

If I where you I would not use your (partial) LFS build to test this: Use your host.

You do need to remove both the build and source directory before starting the next test. Here's how I did the quick test: You cannot use fractions for X, so with having one core in mind I would use 1,2 and 3 for X.

I've learnt that one should use the amount of cpus +1. I have 4 cpus (2 physical and 2 virtual). This is what I got when I did the same test with binutils:

So for me -j5 was fastest.