Re: Linux v2.6.18-rc1: printk delays

[Tilman Schmidt]

With kernel 2.6.18-rc1 I am experiencing strange delays before printk
messages from my driver appear in the syslog. The last couple of printk
lines only appear if I hit a key on the system keyboard. Even just
pressing and releasing a shift key will do. Other input, like connecting
with ssh from another computer and typing into that session or moving or
clicking the mouse, doesn't help. At the same time, userspace syslog
messages like those from sshd appear just fine.

Example excerpt from /var/log/messages:

> Jul  7 00:16:08 gx110 kernel: [  746.583136] gigaset: 0: if_write()
> Jul  7 00:16:08 gx110 kernel: [  746.583154] gigaset: CMD Transmit (10 bytes):
> Jul  7 00:16:08 gx110 kernel: [  746.583203] bas_gigaset: setting ATREADY time
> Jul  7 00:16:08 gx110 kernel: [  746.585887] bas_gigaset: write_command: sent 
> Jul  7 00:16:08 gx110 kernel: [  746.612869] gigaset: received response (6 byt
> Jul  7 00:16:28 gx110 sshd[6134]: Accepted publickey for ts from 192.168.59.12
> Jul  7 00:28:26 gx110 kernel: [  746.687844] gigaset: 0: if_write()
> Jul  7 00:28:26 gx110 kernel: [  746.687944] gigaset: CMD Transmit (17 bytes):
> Jul  7 00:28:26 gx110 kernel: [  746.688002] bas_gigaset: setting ATREADY time
> Jul  7 00:28:26 gx110 kernel: [  746.690803] bas_gigaset: write_command: sent 

Note how the PRINTK_TIME timestamps increase in sub-second increments
while syslogd's timestamps show an enormous gap after 00:16:08.

With kernel 2.6.17.1 on the same machine there are no such delays. All
printk messages appear immediately, and the deltas in PRINTK_TIME and
syslogd timestamps are quite consistent.

Regards
Tilman

-- 
Tilman Schmidt                                    E-Mail: tilman@xxxxxxx
Bonn, Germany
It is well known that a vital ingredient of success is not knowing that
what you're attempting can't be done. [Terry Pratchett, Equal Rites]

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