OpenJDK ARM build not using all the CPU cores

[Erik Joelsson]

If you want to do the override at configure time, the correct configure 
parameter is --with-jobs=4. The --with-num-cores isn't all that useful 
except for easier testing of the logic for calculating the default 
number of jobs (which is why I left it there).

The default limitation of jobs based on memory is rather conservative (1 
job per 1024MB IIRC). We don't like to assume that building is the only 
thing the system ever does. Also most of the build tasks aren't that 
memory hungry, but some are. I recommend you try manually increasing 
jobs until you find your optimal level of concurrency for the types of 
builds you do.

/Erik


On 2017-04-19 11:07, Ioi Lam wrote:
> If you really want, you can override the settings with
>
> make JOBS=4 images
>
> Of course, YMMV due to the low amount of memory.
>
> Ioi
>
>> Mani Sarkar <sadhak001 at gmail.com> 於 2017年4月19日 下午4:07 寫道：
>>
>> Thanks Andrew for clarifying.
>>
>>> On Wed, 19 Apr 2017 at 08:56 Andrew Haley <aph at redhat.com> wrote:
>>>
>>>> On 19/04/17 08:42, Mani Sarkar wrote:
>>>> Whilst build OpenJDK (latest version from
>>>> http://hg.openjdk.java.net/jdk8u/jdk8u/), we have noticed, that the
>>> build
>>>> system does not make use of all the CPU cores available on the machine
>>> even
>>>> though it detects them all.
>>> It's because you have almost no memory installed.  If you want to
>>> override the number of cores to use you can do so manually, but the
>>> idea is to prevent you from running out of memory during the build.
>>> It's deliberate, not a bug.
>>>
>>> Andrew.
>>>
>>> --
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