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    SubjectRe: [QUICKLIST 1/4] Quicklists for page table pages V5
    On Mon,  9 Apr 2007 11:25:09 -0700 (PDT)
    Christoph Lameter <clameter@sgi.com> wrote:

    > Quicklists for page table pages V5
    >
    > ...
    >
    > +/*
    > + * The two key functions quicklist_alloc and quicklist_free are inline so
    > + * that they may be custom compiled for the platform.
    > + * Specifying a NULL ctor can remove constructor support. Specifying
    > + * a constant quicklist allows the determination of the exact address
    > + * in the per cpu area.
    > + *
    > + * The fast patch in quicklist_alloc touched only a per cpu cacheline and
    > + * the first cacheline of the page itself. There is minmal overhead involved.
    > + */
    > +static inline void *quicklist_alloc(int nr, gfp_t flags, void (*ctor)(void *))
    > +{
    > + struct quicklist *q;
    > + void **p = NULL;
    > +
    > + q =&get_cpu_var(quicklist)[nr];
    > + p = q->page;
    > + if (likely(p)) {
    > + q->page = p[0];
    > + p[0] = NULL;
    > + q->nr_pages--;
    > + }
    > + put_cpu_var(quicklist);
    > + if (likely(p))
    > + return p;
    > +
    > + p = (void *)__get_free_page(flags | __GFP_ZERO);
    > + if (ctor && p)
    > + ctor(p);
    > + return p;
    > +}
    > +
    > +static inline void __quicklist_free(int nr, void (*dtor)(void *), void *p,
    > + struct page *page)
    > +{
    > + struct quicklist *q;
    > + int nid = page_to_nid(page);
    > +
    > + if (unlikely(nid != numa_node_id())) {
    > + if (dtor)
    > + dtor(p);
    > + free_page((unsigned long)p);

    free_page() has to run virt_to_page(), but we already have the page*.

    > + return;
    > + }
    > +
    > + q = &get_cpu_var(quicklist)[nr];
    > + *(void **)p = q->page;
    > + q->page = p;
    > + q->nr_pages++;
    > + put_cpu_var(quicklist);
    > +}
    > +
    > +static inline void quicklist_free(int nr, void (*dtor)(void *), void *pp)
    > +{
    > + __quicklist_free(nr, dtor, pp, virt_to_page(pp));
    > +}
    > +
    > +static inline void quicklist_free_page(int nr, void (*dtor)(void *),
    > + struct page *page)
    > +{
    > + __quicklist_free(nr, dtor, page_address(page), page);
    > +}

    All this (still) seems way too big to be inlined. I'm showing a 20-odd
    byte reduction in x86_64's memory.o text when it is uninlined. Pretty
    modest I guess.

    -
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