Re: Why :O?

[der Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>>> SYSTEM_DEP?=    Makefile ${SYSTEM_OBJ:O} .gdbinit
>>> Why is the :O there?
>> revision 1.75
>> date: 2006/04/19 07:06:22;  author: lukem;  state: Exp;  lines: +2 -2
>> Sort SYSTEM_OBJ before adding to SYSTEM_DEP.
>> Kernel builds are now more consistent with userland
>> (and IMHO building in order is more asthetically pleasing.)
> Hmm.  IIRC, the reason this change was made in userland was so that
> all the variants of a single file (.ln, .o, .po, .so, etc) would be
> built in order, maximizing cache hits.

That's my own understanding, too.

> It sounds like this change to the kernel builds is actually hurting
> cacheability, by jumping back and forth from directory to directory.

That's my perception.  I have not, admittedly, actually measured any
such impact, but if it made a measurable difference to userland, I
would expect it to make a measurable difference to kernel builds too.
(Well, except that it takes less RAM to hold the whole source tree in
core and thus hide any such difference.)

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