[fpc-devel] Comparison FPC 2.6.2 - Delphi 7

[Mark Morgan Lloyd]

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]