On Thu, Feb 15, 2024 at 03:19:33PM -0800, Dave Hansen wrote: > On 2/15/24 15:07, Steven Rostedt wrote: > > 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.
