On 19.12.24 17:52, Matthew Wilcox wrote:
On Thu, Dec 19, 2024 at 05:33:32PM +0100, David Hildenbrand wrote:
On 19.12.24 17:22, Matthew Wilcox (Oracle) wrote:
These two patches compile ... I can promise nothing more than that.
David suggested to me that the gmap code really should be using ptdesc,
and I think I agree with him. The vsie code looks quite different
and probably shouldn't be using a ptdesc, but we can use page->private
instead of page->index. It's not yet clear to me if we'll ever manage
to get rid of page->private.
Just curious, does that mean that memdesc would always contain these
additional 8 bytes?
Eventually we'll have a choice to make.
1. Shrink struct page to 8 bytes, but we'll need to allocate a 32 byte
memdesc for all the current users of page->private
2. Shrink struct page to 16 bytes
I genuinely don't know which will be better for the whole system.
If you're asking because we can defer some of the mapcount
work by using the 8 bytes of page->private to store mapcount, then
yes, let's do that.
Yeah, it could give us a bit more time, until we know that we can just
get rid of it in all kernel configs. But let's see if that is still a
problem when we're getting closer to removing them.
--
Cheers,
David / dhildenb
