On Mon, Mar 01, 2021 at 12:16:19PM -0800, Hugh Dickins wrote:

On Mon, 1 Mar 2021, Yu Zhao wrote:

quoted

On Mon, Mar 01, 2021 at 02:50:07PM +0300, Kirill A. Shutemov wrote:

quoted

On Fri, Feb 26, 2021 at 12:13:14PM +0000, Matthew Wilcox wrote:

quoted

On Fri, Feb 26, 2021 at 02:17:18AM -0700, Yu Zhao wrote:

quoted

All places but one test, set or clear PG_active and PG_unevictable on
small or head pages. Use compound_head() explicitly for that singleton
so the rest can rid of redundant compound_head().

How do you know it's only one place?  I really wish you'd work with me
on folios.  They make the compiler prove that it's not a tail page.

+1 to this.

The problem with compound_head() is systemic and ad-hoc solution to few
page flags will only complicate the picture.

Well, I call it an incremental improvement, and how exactly does it
complicate the picture?

I see your point: you prefer a complete replacement. But my point is
not about the preference; it's about presenting an option: I'm not
saying we have to go with this series; I'm saying if you don't want
to wait, here is something quick but not perfect.

+1 to this.

page folios are here and ready to go.  I'm doing another pass on them,
quantifying the improvements to text with each patch.  So far I'm
at 4357 bytes of text saved, in the first 10 patches (many of which
look as if they're not going to produce any savings).

Yu Zhao's patches seem risky.  The only way to know if any places have
been missed is by enabling CONFIG_DEBUG_VM_PGFLAGS, which we do not
recommend for production environments.