Re: [RESEND PATCH v1 1/2] trace: events: scsi: Add tag in SCSI trace events

[Bart Van Assche]

On Mon, 2018-04-16 at 21:10 +0000, Bean Huo (beanhuo) wrote:
> Hi, Bart
> 
> > mingo@xxxxxxxxxx; linux-block@xxxxxxxxxxxxxxx; rajatja@xxxxxxxxxx
> > Subject: [EXT] Re: [RESEND PATCH v1 1/2] trace: events: scsi: Add tag in SCSI
> > trace events
> > 
> > On Mon, 2018-04-16 at 14:31 +0000, Bean Huo (beanhuo) wrote:
> > >  	TP_printk("host_no=%u channel=%u id=%u lun=%u data_sgl=%u
> > 
> > prot_sgl=%u" \
> > > -		  " prot_op=%s cmnd=(%s %s raw=%s)",
> > > +		  " prot_op=%s tag=%d cmnd=(%s %s raw=%s)",
> > > 
> > > [ ... ]
> > >  	TP_printk("host_no=%u channel=%u id=%u lun=%u data_sgl=%u
> > 
> > prot_sgl=%u" \
> > > -		  " prot_op=%s cmnd=(%s %s raw=%s) rtn=%d",
> > > +		  " prot_op=%s tag=%d cmnd=(%s %s raw=%s) rtn=%d",
> > > [ ... ]
> > >  	TP_printk("host_no=%u channel=%u id=%u lun=%u data_sgl=%u " \
> > > -		  "prot_sgl=%u prot_op=%s cmnd=(%s %s raw=%s)
> > 
> > result=(driver=" \
> > > -		  "%s host=%s message=%s status=%s)",
> > > +		  "prot_sgl=%u prot_op=%s tag=%d cmnd=(%s %s raw=%s) " \
> > > +		  "result=(driver=%s host=%s message=%s status=%s)",
> > 
> > Which tools process these strings? Has it been verified whether or not the
> > tools that process these strings still work fine with this patch applied?
> > 
> 
> I don't use one certain special tool to analyze this string, I am using ftrace with event.
> With tag information, I can see how many tasks in storage device and easily to trace each request
> under multiple thread workload. 
> Event there is someone who using certain tool to analyze this string, after adding additional
> tag printout, in my opinion, they are happy to see it there. 

Since you want to change these strings it is your job to determine which
user space tools parse these strings and also whether or not this change
will break any of these tools.

Thanks,

Bart.