Re: SMP kernels /w POLLING enabled - combination garbles(syncer?) console line message(s) on reboot

Steven Hartland wrote:
----- Original Message ----- From: "Chargen" <chargen@xxxxxxxxx>
To: <freebsd-current@xxxxxxxxxxx>
Sent: Saturday, January 26, 2008 4:36 AM
Subject: 7cur: SMP kernels /w POLLING enabled - combination garbles(syncer?) console line message(s) on reboot


7cur: SMP kernels /w POLLING enabled - combination garbles (syncer?) console
line message(s) on reboot

SMP kernel with POLLING enabled garbles one or more of the last lines in
console after issuing the {reboot} command

options DEVICE_POLLING
options HZ=1000

with or without sysctl -w kern.polling.enable=1 or sysctl -w
kern.polling.enable=0

The garbled lines are between 'shutting down bufdaemon' and 'all buffs
synced' (after 'bufdaemon', I presume these are the syncer, 'Syncing
disks, vnodes synced' lines)

I found it only reproducable with SMP /apic enabled kernel. Console messages
after issuing reboot on UP kernels with polling_enabled are readable.

Note: polling wasn't manually set on any device (tested on UP and SMP
kernels) e.g.: no ifconfig em0 polling


Funny you should say that. Noticed that last night when rebooting one of
our new 7.0 machines but assumed it was a one off remote console corruption.

Just tested this again and its not. So I can confirm the corruption here
on 7.0-PRERELEASE amd64 without polling.

It's harmless (actually a sign of increased concurrency); two threads are running printf concurrently. Add options PRINTF_BUFR_SIZE=[...] if you don't want to see this.

Kris
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