Messages in this thread | | | Date | Thu, 8 Apr 2004 19:16:12 +0100 (BST) | From | Hugh Dickins <> | Subject | Re: NUMA API for Linux |
| |
On Thu, 8 Apr 2004, Martin J. Bligh wrote: > > On Wed, 7 Apr 2004, Andrew Morton wrote: > >> > >> Your patch takes the CONFIG_NUMA vma from 64 bytes to 68. It would be nice > >> to pull those 4 bytes back somehow. > > > > How significant is this vma size issue? > > > > anon_vma objrmap will add 20 bytes to each vma (on 32-bit arches): > > 8 for prio_tree, 12 for anon_vma linkage in vma, > > sometimes another 12 for the anon_vma head itself. > > Ewwww. Isn't some of that shared most of the time though?
The anon_vma head may well be shared with other vmas of the fork group. But the anon_vma linkage is a list_head and a pointer within the vma.
prio_tree is already using a union as much as it can (and a pointer where a list_head would simplify the code); Rajesh was thinking of reusing vm_private_data for one pointer, but I've gone and used it for nonlinear swapout.
> > anonmm objrmap adds just the 8 bytes for prio_tree, > > remaining overhead 28 bytes per mm. > > 28 bytes per *mm* is nothing, and I still think the prio_tree is > completely unneccesary. Nobody has ever demonstrated a real benchmark > that needs it, as far as I recall.
I'm sure an Ingobench will shortly follow that observation.
Hugh
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |