Re: [RFC v2 PATCH 2/4] block: add queue runtime pm callbacks

Alan Stern
2012-05-24T14:52:37Z

On Thu, 24 May 2012, Lin Ming wrote:

> > When tested the patches, I found that kjournald and flusher thread
> > frequently resume the disk.
>
> Just found that it's because "printk".
>
> When disk is suspended, it prints out some message, for example,
>
> [ 670.597103] sd 0:0:0:0: [sda] Synchronizing SCSI cache
> [ 670.597827] sd 0:0:0:0: [sda] Stopping disk
>
> Then syslogd is waken up to write the log.
> So disk is resumed right after suspended.

:-) Very amusing! So if you change those two messages in sd_suspend
(and maybe also the message in sd_resume) from KERN_NOTICE to
KERN_DEBUG, things ought to improve.

Alan Stern