Re: build.sh: set creation is serialized

[Alan Barrett <apb%netbsd.org@localhost>]

On Wed, 30 Apr 2008, Andrew Doran wrote:
>> In src/src/distrib/sets/Makefile:
>> Serialise making the "sets" tarballs in the maketars target.
>> On many systems, making them in parallel causes very poor
>> system performance due to disk I/O.  (Requested by jmmv.)

> My system is not affected, but if it were I don't see
> why any of these would not be a valid solution:
> 
> o use smaller value for -j
> o analyze the problem on the affected systems
> o buy more spindles

"Analyse and fix the problem" is the only solution that appeals to me.

On my system, the disk scheduler still seems to work very badly in the
face of multiple consecutive tasks.  (One spindle, ffs on cgd on wd.)
One task doing heavy disk I/O (rm -rf a large directory tree, cp -RPp a
large tree, unpack a tarball with many files) causes other tasks that
try to access the disk to experience very bad performance.  Multiple
simultaneous disk-intensive tasks makes the system almost unusable for
interactive work.

--apb (Alan Barrett)