Re: [PATCH v4 00/34] Printbufs - new data structure for building strings

[Kent Overstreet]

On Mon, Jun 20, 2022 at 05:38:51PM -0700, Joe Perches wrote:
> On Mon, 2022-06-20 at 11:07 -0400, Kent Overstreet wrote:
> > On Mon, Jun 20, 2022 at 04:19:31AM +0000, David Laight wrote:
> > > I really think that is a bad idea.
> > > printk() already uses a lot of stack, anything doing a recursive
> > > call is just making that worse.
> > > Especially since these calls can often be in error paths
> > > which are not often tested and can already be on deep stacks.
> > 
> > We went over this before - this patch series drastically reduces stack usage of
> > sprintf by eliminating a bunch of stack allocated buffers. Do try to keep up...
> 
> I generally agree with David.
> 
> I think Kent has not provided data that this actually _reduces_
> stack usage.

I think the people who are comfortable with reading C can discern that when
large stack allocated character arrays are deleted, frame size and stack usage
go down.