Re: [PATCH v6 5/6] mm: secretmem: use PMD-size pages to amortize direct map fragmentation

From: Peter Zijlstra
Date: Wed Sep 30 2020 - 06:44:15 EST


On Wed, Sep 30, 2020 at 01:20:31PM +0300, Mike Rapoport wrote:

> I tried to dig the regression report in the mailing list, and the best I
> could find is
>
> https://lore.kernel.org/lkml/20190823052335.572133-1-songliubraving@xxxxxx/
>
> which does not mention the actual performance regression but it only
> complaints about kernel text mapping being split into 4K pages.
>
> Any chance you have the regression report handy?

I think the saga started here:

20190820075128.2912224-1-songliubraving@xxxxxx
20190820202314.1083149-1-songliubraving@xxxxxx
20190823052335.572133-1-songliubraving@xxxxxx

After that Thomas did the patch I referred to earlier and I endeavoured
to rewrite x86-ftrace.

I added Song to CC, maybe he can remember more.