On Thu, May 03, 2018 at 10:03:10AM -0500, Christopher Lameter wrote:
> On Wed, 2 May 2018, Matthew Wilcox wrote:
>
> > > > Option 2:
> > > > + union {
> > > > + unsigned long counters;
> > > > + struct {
> > > > + unsigned inuse:16;
> > > > + unsigned objects:15;
> > > > + unsigned frozen:1;
> > > > + };
> > > > + };
> > > >
> > > > Pro: Expresses exactly what we do.
> > > > Con: Back to five levels of indentation in struct page
>
> I like that better. Improves readability of the code using struct page. I
> think that is more important than the actual definition of struct page.
OK. Do you want the conversion of slub to using slub_freelist and slub_list
as part of this patch series as well, then?
The end result looks like this, btw:
struct { /* slub */
union {
struct list_head slub_list;
struct {
struct page *next; /* Next partial */
#ifdef CONFIG_64BIT
int pages; /* Nr of pages left */
int pobjects; /* Apprx # of objects */
#else
short int pages;
short int pobjects;
#endif
};
};
struct kmem_cache *slub_cache; /* shared with slab */
/* Double-word boundary */
void *slub_freelist; /* shared with slab */
union {
unsigned long counters;
struct {
unsigned inuse:16;
unsigned objects:15;
unsigned frozen:1;
};
};
};
Oh, and what do you want to do about cache_from_obj() in mm/slab.h?
That relies on having slab_cache be in the same location in struct
page as slub_cache. Maybe something like this?
page = virt_to_head_page(x);
#ifdef CONFIG_SLUB
cachep = page->slub_cache;
#else
cachep = page->slab_cache;
#endif
if (slab_equal_or_root(cachep, s))
return cachep;
> Given the overloaded overload situation this will require some deep
> throught for newbies anyways. ;-)
Yes, it's all quite entangled.
