[llvm-dev] Recommended computer resources to build llvm

Wink Saville via llvm-dev
Tue, 06 Sep 2016 22:21:48 -0000

Yes, it did appear to be in the linking steps and initially I had only
a 240MB swap on my SSD and the build failed and my chromium browser
tabs all died, probably because of CPU starvation. I then added a 16GB
swap file on a HD and computer still got very slow as the resources
got used up and it was tough to do anything on the computer even
control C took a minute or more to abort the compilation. I tried -j8
more or less the same thing so I then dropped to -j2 and finally it
succeeded.

So it sounds like for 12 CPU's I should bump up the RAM size.

And the tip about changing -j for linker might also bear some fruit.

Thanks.



On Tue, Sep 6, 2016 at 3:06 PM, Bruce Hoult <bruce at hoult.org>
wrote:
> That's a reasonably well resourced machine, though the last couple of
years
> I've been spec'ing quad core (plus HT) machines with 32 GB rather
than 16
> GB, and you've got 50% more cores.
>
> Still that should be plenty for 12 compiler instances. I suspect the
problem
> is something else, such as link steps.
>
> I haven't looked at the actual ninja rules, but you can specify a
smaller
> "-j" setting for particular kinds of build steps. See:
>
> https://ninja-build.org/manual.html#ref_pool
>
> I have no idea whether the llvm ninja rules currently include something
like
> that.
>
>
> On Wed, Sep 7, 2016 at 9:54 AM, Wink Saville via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>>
>> I've got a i7 with 12 logical cores and 16GB of RAM I successfully
>> built RELEASE_390/final but for the last 100 or so files I'd to use
>> "ninja -j2" so as not to keep from swapping in the best case
and and
>> in the worst case the build kills itself without completing because
>> apparently its run out of memory.
>>
>> For the first 3200 files or so it was doing just fine with
"ninja"
>> which is probably "ninja -j12" but as I said for the last 100
or so
>> files I had to use "ninja -j2" to get it to complete.
>>
>> So what is the recommended computer resources, and I guess RAM size in
>> particular, for building llvm "quickly"?
>>
>> -- wink
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>
>