Using /tmp to store GCC temp. files while kernel compiles?

[VinzC]

Hi all.

I'm configuring a Gentoo machine with a SSD and a mechanical disk, both are SATA drives. I've used the mechanical drive to store /var, portage files and, well, mainly as much as possible of files that [are supposed to] change a lot of times. However as /usr belongs to the SSD, I wonder if I can optimize even further by sending all temporary compile results to somewhere like /tmp or even a tmpfs when I'm compiling the kernel.

For kicks I've tried setting TMPDIR to /tmp in a file under /etc/env.d/ but it doesn't seem to work (I see no temporary file pop in /tmp). In case you wonder, yes I've even rebooted the machine to have a proper starting point and TMPDIR is indeed set to /tmp. Can it be done at all? and how?

Thanks in advance for any hint/suggestion.
_________________
Gentoo addict: tomorrow I quit, I promise!... Just one more emerge...
1739!

[John R. Graham]

How about mounting /usr/src to some partition or directory on your rotating rust? Do you consider .o files to be temporary? If so, I believe it'd take modifications to the source to achieve what you're literally asking about.

- John
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I can confirm that I have received between 0 and 499 National Security Letters.

[Naib]

bind mount
mount --bind /usr/src /tmp/kernel_buiild
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[krinn]

yeah, trying to force TMPDIR=/tmp is ... just what /tmp is made for

those are temp files for you, not really temporary files for kernel, that re-use them on next compile if they haven't change.
and it might (or not) use /tmp itself for some files that are really just garbage, but it's something most users won't see because they have cflags set with -pipe which is to avoid that.

[VinzC]

[John R. Graham]

FYI, the kernel makefile doesn't honor (nor know about) make.conf, which is purely a Gentooism. It does honor CFLAGS in the environment, though, so

[NeddySeagoon]

<nit>
CFLAGS=-pipe is an advisory not an instruction to gcc.
It means to use pipes between compile phases if memory permits.
</nit>

gcc will silently write intermediate files to hdd if there is not enough RAM to honour the -pipe advisory.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

[Ant P.]

I wouldn't bother with all this, just tweak laptop_mode and related sysctls and the kernel will avoid writing to disk on its own.

[VinzC]

Well, thanks for all the hints, guys.

[grumblebear]

What sort of optimizing is that? A SSD is not as fragile as you might think. Even with the portage tree and daily kernel compiles it will normally last for many, many years.

Besides speaking from personal experience, you can also explore the great wisdom Google has to offer on that topic.

[mv]

[mv]

[VinzC]

[grumblebear]

It just sounded to me as if you were concerned about the lifetime of your SSD. So excuse me for being a little off-topic, but the myths about writing to SSDs are going around a little too long for my taste.

I just want to point out to anyone reading this, that it is just not worth too much effort to avoid writing to SSDs. Even in your case, whatever it might be, I highly doubt you will even get a single year additional lifetime. The propability is much higher that some part of the electronics gets damaged or even the SATA standard gets replaced before the flash cells wear out.

PS
To get back on-topic: You can unpack and compile the kernel sources anywhere you like. Just don't forget to make modules_install and put the kernel image where your bootloader expects to find it. And of course you should put /lib/modules on your mechanical drive or compile a monolithic kernel.

[VinzC]