Re: [ANNOUNCE] Linux Kernel Useful Patches (2.4)

["Barry K. Nathan" <barryn@pobox.com>]

On 2/4/06, Willy TARREAU <willy@w.ods.org> wrote:
> The last O(1) patch I've seen does not apply to kernels more recent than 2.4.19
> (it's on Ingo's site). Do you have any up to date pointer that I could use ?
> However, I have a local rediff of the lowlat patch that I will include.

(This e-mail ended up being a bit longer than I intended. The most
relevant stuff may be in the last couple of paragraphs, but I've
included the whole message for the sake of completeness.)

Red Hat ships it in a 2.4.21-based kernel. Here's their latest source RPM:
ftp://ftp.redhat.com/pub/redhat/linux/updates/enterprise/3AS/en/os/SRPMS/kernel-2.4.21-37.0.1.EL.src.rpm

However, I just remembered that the RHEL 3 kernel patch series starts
with an -ac patch and builds up from there. I think it gets the O(1)
scheduler from there but it might apply further patches to it (but I'm
not 100% sure my memory is correct here).

Here's the last -ac patch:
http://kernel.org/pub/linux/kernel/people/alan/linux-2.4/2.4.22/patch-2.4.22-ac4.bz2

If you want to see what Red Hat/Fedora did against 2.4.22, this is
what the final Fedora Core 1 kernel shipped:
http://cvs.fedora.redhat.com/viewcvs/rpms/kernel/FC-1/
(There are newer kernels for FC1 from Fedora Legacy, but I think those
just add security fixes.)

There's also 2.4.27-pre2-pac1, which has the O(1) scheduler. I don't
know if it introduces any bugs into the O(1) scheduler though. (It did
introduce a bug into the overcommit accounting, because part of it was
missing.)
http://kernel.org/pub/linux/kernel/people/bero/2.4/2.4.27/patch-2.4.27-pre2-pac1.bz2

Finally, 2.4.31-lck1 has the O(1) scheduler. This is the "base" patch
for 2.4.31-lck1, which has O(1) but also has "kernel preemption, low
latency and CK interactivity":
http://www.plumlocosoft.com/kernel/patches/2.4/2.4.31/2.4.31-lck1/components/010-lckbase.diff.bz2

It's probably the most recent forward-port of the O(1) patch, and it's
probably going to be the smallest diff to look through as well, if you
want to cherry-pick it out and make it work on 2.4.32 or 2.4.33-pre.
(I don't think I'll be doing this, however. The boxes I manage that
would greatly benefit from O(1) will probably move to kernel 2.6 soon
for other reasons anyway.)
--
-Barry K. Nathan <barryn@pobox.com>