On Thu, 25 Nov 2004 16:19:02 +0900, Rob <[EMAIL PROTECTED]> wrote:
Rob wrote:Brian Szymanski wrote:
Did you try any machines that used Hyperthreading? I'd be interested to
see how those machines fare based on the number of logical and real CPUs.
Although people suggest "-j4" as optimal in general case, I have come to a very different conclusion:
1) single CPU with enough RAM (2 GHz, 512 MB) there's no significant speed up in the range "-j1" to "-j9". So "-j1" is as good as "-j9".
If you went to all that trouble, you might as well post the numbers :-)Time unit is minutes. CPU: 2x800 MHz 2000 MHz 333 MHz RAM: 1024 MB 512 MB 64 MB -j -------------------------------- 1 99 50 276 2 58 49 291 3 58 50 367 4 57 50 547 5 58 49 6 58 50 7 57 50 8 58 50 9 58 50
I have run another test on a 700 MHz, 128 MB PC, and the following equation seems to hold for all my tests. Calculate:
time(minutes) * speed(MHz) * nproc / 1000 MHz
and if this results in approximately 1, the system is optimized.
For example, in the above case,
column 1: -j1 : 99 * 800 * 2 / 1000 = 1.5 -j2 : 58 * 800 * 2 / 1000 = 0.928
column 2: -j1 : 50 * 2000 * 1 / 1000 = 1
column 3: -j1 : 276 * 333 * 1 / 1000 = 0.919
another PC: -j1 : 142 * 700 * 1 / 1000 = 0.994
--------------
All PCs have "standard" hardware. Off-the-shelf mainboard, IDE harddisks, nothing special really.
All this is done on 5.3-Stable systems and the time listed (in minutes) is for the buildworld only: "make -jn buildworld"
Rob.
Would all this work for 'make index' for the ports also? Or is this more io bound?
I can't test this myself, because my laptop is to slow for making these tests any fun.
Ronald.
-- Ronald Klop, Amsterdam, The Netherlands _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "[EMAIL PROTECTED]"
