Fleshing out memory descriptors

Posted May 27, 2024 16:09 UTC (Mon) by willy (subscriber, #9762)
In reply to: Fleshing out memory descriptors by willy
Parent article: Fleshing out memory descriptors

Hm, now I re-read the article, it's a little confusing and I see how someone could come away with the impression that there is.

There is not. I do not propose ever allocating a struct buddy.

That's clear in the wiki pages, I hope. And if it is, then I'll remedy that.

Fleshing out memory descriptors

Posted May 27, 2024 18:29 UTC (Mon) by pbonzini (subscriber, #60935) [Link] (1 responses)

It is clearer in the wiki, yes:

struct page {
    union {
        unsigned long memdesc;
        struct buddy buddy;
    };
};

Would it make sense to tackle the "private" field _last_ (not first) by sticking it in the second word of struct page, that is:

struct page {
    unsigned long memdesc_or_next;
    unsigned long private_or_prev;
};

Fleshing out memory descriptors

Posted May 27, 2024 18:56 UTC (Mon) by willy (subscriber, #9762) [Link]

Oh, interesting idea. That's a path to getting us to a 16 byte struct page sooner. I like it. There's various other work to be done to remove the use of page->flags (mostly things like looking up the zone/node/etc), but that needs to happen anyway.