On 24/07/15 10:54, Julien Grall wrote: > On 24/07/15 10:31, David Vrabel wrote: >> On 09/07/15 21:42, Julien Grall wrote: >>> The Xen interface is always using 4KB page. This means that a Linux page >>> may be split across multiple Xen page when the page granularity is not >>> the same. >>> >>> This helper will break down a Linux page into 4KB chunk and call the >>> helper on each of them. >> [...] >>> --- a/include/xen/page.h >>> +++ b/include/xen/page.h >>> @@ -39,4 +39,24 @@ struct xen_memory_region >>> xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS]; >>> >>> extern unsigned long xen_released_pages; >>> >>> +typedef int (*xen_pfn_fn_t)(struct page *page, unsigned long pfn, void >>> *data); >>> + >>> +/* Break down the page in 4KB granularity and call fn foreach xen pfn */ >>> +static inline int xen_apply_to_page(struct page *page, xen_pfn_fn_t fn, >>> + void *data) >> >> I think this should be outlined (unless you have measurements that >> support making it inlined). > > I don't have any performance measurements. Although, when Linux is using > 4KB page granularity, the loop in this helper will be dropped by the > helper. The code would look like: > > unsigned long pfn = xen_page_to_pfn(page); > > ret = fn(page, fn, data); > if (ret) > return ret; > > The compiler could even inline the callback (fn). So it drops 2 > functions call.
Ok, keep it inlined. >> Also perhaps make it >> >> int xen_for_each_gfn(struct page *page, >> xen_gfn_fn_t fn, void *data); > > gfn standing for Guest Frame Number right? Yes. This suggestion is just changing the name to make it more obvious what it does. David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
