Re: cvs commit: src/sys/kern sched_ule.c (fwd)

Tony Arcieri wrote:
> On 2004-12-13 17:26:10 Scott Long wrote:
>> RELENG_5 is the stable branch.  If quality testing goes into ULE in HEAD
>> and it's shown to be as stable as 4BSD then we can consider it for
>> RELENG_5 in the future.  Given the incredible problems that we had in
>> the scheduler leading up to 5.3, I'm not excited about quickly merging
>> these things.
>
> I have FreeBSD 5.3 installed on a dual amd64 colo server of mine and have
> been experiencing severe issues with the system and the 4BSD scheduler
> under heavy MySQL load.  Originally with 5.3-RELEASE these appeared to be
> kernel crashes/deadlocks, but unfortunately I never had a dump device
> configured when I was running 5.3-RELEASE and so I don't have a core file
> to be examined.
>
> However, I've been checking out the sys/ sources from RELENG_5 fairly
> frequently and still experience severe issues with the 4BSD scheduler
> when the system is under heavy database load.  Namely, while the kernel
> appears to remain running and the system continues to respond to pings,
> all other network services cease to function.  New TCP connections are
> accepted, but the services don't respond, and existing connections time
> out.
>
> I have found this does NOT occur when the ULE scheduler is used.  I have
> (perhaps foolishly) attempted to copy the minimum necessary files to run
> the ULE scheduler from the -CURRENT branch and merge them myself into the
> 5-STABLE sources, which I believe are sched_ule.c and kern_switch.c, and
> have modified the proc_fini() function in kern_proc.c to panic if invoked
> (since according to the comments, UMA should ensure that proc_fini is
> never called, correct?).  If these are all the changes that are needed to
> import the ULE scheduler, then why continue to include the broken ULE
> scheduler with an #error tag rather than importing the minimum sources
> required for the ULE scheduler to work and leave it off per default?
>
> I, for one, am experiencing better system stability with ULE than with
> 4BSD.
> If anyone cares to examine my system I can provide shell access.

I thought about trying this last night when I saw that ULE was
resurrected.  Make sure you also grab kern_sig.c:
http://lists.freebsd.org/pipermail/cvs-src/2004-December/036757.html

I can't say whether those 3 files are all you need, just that I would also
include kern_sig.c... ;-)

Jon