mbuf revision, testers/comments wanted.

[Fabian Keil]

Jeff Roberson <jroberson at jroberson.net> wrote:

> On Sun, 1 Feb 2009, Fabian Keil wrote:
> 
> > Fabian Keil <freebsd-listen at fabiankeil.de> wrote:
> >
> >> Jeff Roberson <jroberson at jroberson.net> wrote:
> >>
> >>> http://people.freebsd.org/~jeff/mbuf_ref2.diff
> >>
> >>> I have been experimenting with different revisions to the mbuf api to
> >>> improve performance and simplify code.  This patch is the first of
> >>> several proposed steps towards those goals.  The aim of this patch is
> >>> two fold;
> >>
> >>> I would appreciate testing feedback from varied workloads to make sure
> >>> there are no bugs before I go forward with this.  I have tested only
> >>> host oriented networking with a few drivers.  It is not anticipated
> >>> that there will be any significant incompatibilities introduced with
> >>> this round but there is always that possibility.
> >
> >> 5)
> >> Finally, I tested the patch on an IBM ThinPad R51. The kernel
> >> hangs on boot, the last messages are (hand transcribed):
> >>
> >> iwi0: <Intel(R) PRO/Wireless 2200BG> mem 0xc0214000-0xc0214fff irq 11 at device 2.0 on pci2
> >> iwi0: Reserved 0x1000 bytes for rid 0x10 type 3 at 0xc0214000
> >> iwi0: could not allocate rx mbuf
> >> iwi0: could not allocate Rx ring
> >> bpfdetach: was not attached
> >
> > Never mind, kernel and user land weren't completely in
> > sync and this might be related to the recent wlan commits.
> > I'll retry with an up-to-date user land.

> I have updated the patch here:
> 
> http://people.freebsd.org/~jeff/mbuf_ref2.diff
> 
> This resolves the !INVARIANTS bug and improves the style as you suggested.

I run into several system hangs (or maybe panics) yesterday,
mostly with Xorg running so I didn't get any details.

I got one on the console though. After running a regression
test that opens multiple HTTP connections to the loop back
device, I used rsync to restore some files that were damaged by
an earlier hang. That lead to a page fault in em_start_locked().

While I dumped core from the debugger,
savecore didn't find the dump afterwards.

Anyway, there's a screen shot available at:
http://www.fabiankeil.de/bilder/freebsd/mbuf-patch-page-fault-em_start_locked.jpg

Before the patch I didn't see any surprising panics
in quite a while. I reverted the patch for now to
verify that the system is stable without it.

Fabian
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