On Fri, 09 Apr 2021 07:32:12 +0900 aventador at fastmail.fm wrote:
>It makes me think that there should be an offering for two completely
different audiences:
>(1) FreeBSD core (a very minimal offering for folks that want to build
things, like a Desktop, etc.)
>(2) FreeBSD server (an offering for folks that want a server build)
>
>Perhaps that idea is just unreasonably crazy as well.
>
LOL! You have what is called a very big ask. I would like
something far smaller, namely, a choice of schedulers during/just
after installation of a -RELEASE without having to a) download the
entire source tree, b) make buildworld, and c) make buildkernel.
The kernel developers in their wisdom--ahem--have burdened all new
installations with the abysmal performance of the ULE scheduler.
The installation images for -STABLE versions are much the same.
The 4BSD scheduler has been far from optimal, and the ULE scheduler
looked like a nice idea on paper for newer CPUs, but in fact, the
ULE scheduler's performance is awful, even when compared with the
4BSD scheduler, which generally gives acceptable, though not optimal,
performance.
If the owner of a new installation wants to get passably usable
performance from his new system, he must first perform the tasks
noted above. The second and third tasks will take *a lot* of extra
time because they must be done under the ULE scheduler. Then one
must install the new kernel, reboot, do the mergemaster or /etc/update
steps, install the new world, more mergemaster or /etc/update, and
reboot again.
Two ways of allowing a choice of scheduler are 1) to provide two
GENERIC kernels, e.g., GENERIC.ULE and GENERIC.4BSD, from which one
could choose at boot time, and 2) to compile both schedulers into the
GENERIC kernel, which could be selected from by a loader tunable at
boot time.
The current system is yet another discouragement to upgrading to
a new -RELEASE via a new installation. Further, this fix to bad
performance by default is not documented anywhere. How is a user who
is new to FreeBSD to know about it?
Scott Bennett, Comm. ASMELG, CFIAG
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