Ivanko B wrote:
so that compilation could start while the disk is stressed by loading all other PPU files, required for the compilation of units with more dependencies. ============== Disk I/O is a huge low-down to avoid on any price (like databases do with their indexing). Today me tested building LINUX kernel 3.8.0 on 8*SMT=16 CPU system (Corei7 2G) + 32G DDR3 + 175(wr)/350(rd)MB/s RAID1. And this monster outperformed another cheap E8400 + 4G machine by only 2 times and most probably because the cheap machine was non-RAIDed. And because Core i* arch can't have proper DMA.
I've not had an opportunity to try this, but my understanding is that on a Sun E10K with something like 256 400MHz processors the Linux kernel built in around 20 seconds. I've had it build in about 3 minutes on a system with 16x 80MHz processors, but that was in the days of kernel 2.2 and there was probably less than half today's number of files involved.
make -j has a dramatic effect on an SMP system, particularly if it can find groups of jobs without too much interdependence. If there's a lot of shared input files etc., then my experience is that it tends to level out at around -j 8 since it's extremely difficult to improve the cache architecture beyond that point.
-- Mark Morgan Lloyd markMLl .AT. telemetry.co .DOT. uk [Opinions above are the author's, not those of his employers or colleagues] _______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
