Michael Meyer wrote:


> On mere build servers running linux one could disable
> the second core at boot time permanently to reduce the
> build time, if no other processes are running on this
> server.
>
> But on workstations the second core is often used by
> the application being developed if it is
> multithreaded, so there might be no way in linux to
> reduce the build time wih two cores?


we dont want to turn core #2, off, or even cores #3 and #4. Not when my
memory/process footprint has 3 vmware images (windows for exchange,
centos for release builds, rhel4 for testing and then the IDE on my main
machine)


 PID USER    PR NI VIRT RES SHR S %CPU %MEM   TIME+ COMMAND

9184 slo     18  0 2443m 802m 15m S   0 13.4 84:51.39 java

9129 slo     5 -10 770m 579m 561m S   0 9.7 38:32.89 vmware-vmx

8403 slo     5 -10 768m 570m 556m S  16 9.5 850:09.04 vmware-vmx

8361 slo     15  0 891m 368m 29m S   2 6.2 63:29.62
firefox-bin
9144 slo     5 -10 501m 304m 290m S   0 5.1  6:12.59 vmware-vmx

8253 slo     15  0 373m 251m 22m S   0 4.2 12:02.73
thunderbird-bin
29911 slo     18  0 1641m 177m 12m S   0 3.0  7:42.59 java

5708 root    15  0 314m 167m 59m S   0 2.8 30:08.87 Xorg

24284 slo     17  0 1560m 141m 8692 S   0 2.4  0:35.69 java

19907 slo     15  0 645m 92m 61m S   0 1.6  0:04.22 soffice.bin

11023 slo     15  0 609m 69m 36m S   0 1.2 22:51.60 amarokapp

8304 slo     15  0 384m 54m 28m S   0 0.9  1:47.77 vmware

I had a look at the code and there's no obvious synchronisation in the
javac code. If there is a delay, it may be in the output/listener logic,
which could well be synchronized. On a multicpu system the cost of
acquiring a lock may be higher.

I'd love to track this down, but nothing obvious springs to mind.

-could you try building under vmware/xen? We do that for releases to
ensure the release builds are with clean source, no matter what I'm editing.

-steve

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