Re: [PATCH v4 1/2] nvme: add tracepoint for nvme_setup_cmd

[Johannes Thumshirn]

On Mon, Jan 22, 2018 at 04:59:56PM +0100, Christoph Hellwig wrote:
> On Mon, Jan 22, 2018 at 04:53:56PM +0100, Johannes Thumshirn wrote:
> > Yes and no. I personally like to have the big hammer when tracing customer
> > problems and filter out maunally later. I initially had a tracepoint for each
> > of nvme_setup_flush(), nvme_setup_discard(), nvme_setup_rw() but decided it
> > was too fine grained.
> > 
> > nvme_setup_cmd() has the nice side effect that all commands, including
> > userspace passtrough commands must pass it. This was extremely helpful in the
> > customer bug which inspired me to implement this tracepoint.
> 
> Not arguing against placing the tracepoint(s) in nvme_setup_cmd, but
> it seems like we should have one for admin and one for I/O commands.
> Especially as we have to special case them just about everywhere,
> and the overlap of the opcode space is pretty annoying.

You mean like:
	if (ns)
		trace_nvme_setup_cmd(cmd);
	else
		trace_nvme_setup_admin_cmd(cmd);

?



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Johannes Thumshirn                                          Storage
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