Re: [PATCH v3 31/35] lib: add memory allocations report in show_mem()

On Thu, Feb 15, 2024 at 03:19:33PM -0800, Dave Hansen wrote:

On 2/15/24 15:07, Steven Rostedt wrote:

quoted

Just adding the patches increases the size by 5k. But the rest shows an
increase of 259k, and you are worried about 4k (and possibly less?)???

Doesn't the new page_ext thingy add a pointer per 'struct page', or
~0.2% of RAM, or ~32MB on a 16GB laptop?  I, too, am confused why 4k is
even remotely an issue.

page_ext adds a separate per-page array; it itself does not add a
pointer to strugt page, it's an array lookup that uses the page pfn.

We do add a pointer to page_ext, and that's (for now) unavoidable
overhead - but we'll be looking at referencing code tags by index, and
if that works out we'll be able to kill the page_ext dependency and just
store the alloc tag index in page bits.