RPI4 clock speeds and serial port

[Mark Millard]

On 2021-Mar-21, at 06:50, tech-lists <tech-lists at zyxst.net> wrote:

> On Sat, Mar 20, 2021 at 04:55:47PM -0700, Mark Millard wrote:
> 
>> To me the wording is unclear on an important
>> point:
>> 
>> Was this a rebuild after installing and booting
>> the kernel and world that had been built with
>> those flags? Or was this running the as yet
>> not updated system and just doing the initial
>> build with the -mcpu assignments?
> 
> 1. cd /usr/src && git pull --ff-only
> 2. added those .clang statements to /etc/src.conf
> 3. it had already built world & kernel with the other WITHOUT_xyz    statements in days previously
> 
> this was the first time i'd tried those -mcpu assignments.
> 
> I'll try building again, this time noting exactly what's done.
> 
>> CCACHE status?
> 
> enabled. I almost always use ccache as the buildtime impact is substantial with any c/c++ program. poudriere uses it if it's available
> for this reason.

https://docs.freebsd.org/en_US.ISO8859-1/books/handbook/ports-poudriere.html

reports:

QUOTE
Defining CCACHE_DIR enables the use of devel/ccache to cache compilation and reduce build times for frequently-compiled code.
END QUOTE

and:

# grep -r CCACHE_DIR /usr/local/etc/poudriere.conf.sample
/usr/local/etc/poudriere.conf.sample:#CCACHE_DIR=/var/cache/ccache
/usr/local/etc/poudriere.conf.sample:# Default: yes, unless CCACHE_DIR is set and CCACHE_DIR_NON_ROOT_SAFE is not
/usr/local/etc/poudriere.conf.sample:# use a non-shared CCACHE_DIR that is only built by PORTBUILD_USER and chowned
/usr/local/etc/poudriere.conf.sample:# to that user.  Then set CCACHE_DIR_NON_ROOT_SAFE to yes.

So it looks like use of ccache must be explicitly enabled in
poudriere-devel . Mere installing of devel/cache and then
using poudreire bulk does not seem to use ccache.

(There also seems to be CCACHE_STATIC_PREFIX and
CCACHE_DIR_NON_ROOT_SAFE that can be set as well.)


At least for figuring out what buildworld buildkernel
installs lead to taking less time vs. more time and
how much less/more for later build activity, having
differences in what has been cached by ccache also
involved makes time comparisons untenable.

Of course, going the other way, holding the system
installation constant and doing various without
and with ccache timings for repeatable sequences
of updates can be used to get an idea of how much
ccache can help. I happen to not have done such
testing.


>> Was this caching effectively cleaned-out/empty
>> for the timing?
> 
> I don't know. All I know is that it looks after itself. I'll
> disable/clear out ccache [1] if changing major freebsd versions [2], or tracking down a problem with a program building.
> 
> I'm surprised you don't usually use it
> 
> [1] rm -rf /var/cache/ccache/*
> [2] also rm -rf /usr/obj and re-make it again



===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)