On 7/19/22 2:57 AM, Andrew Turner wrote:
The branch main has been updated by andrew:
URL:
https://cgit.FreeBSD.org/src/commit/?id=36f1526a598c373ca660910c9772d28a61383c3b
commit 36f1526a598c373ca660910c9772d28a61383c3b
Author: Andrew Turner <and...@freebsd.org>
AuthorDate: 2022-03-23 17:39:58 +0000
Commit: Andrew Turner <and...@freebsd.org>
CommitDate: 2022-07-19 09:57:03 +0000
Add experimental 16k page support on arm64
Add initial 16k page support on arm64. It is considered experimental,
with no guarantee of compatibility with a userspace or kernel modules
built with the current a 4k page size as code will likely try to pass
in a too small size when working with APIs that take a multiple of a
page, e.g. mmap.
As this is experimental, and because userspace and the kernel need to
have the PAGE_SIZE macro kept in sync there is no kernel option to
enable this. To test a new image should be built with the
PAGE_{SIZE,SHIFT,MASK} macros changed to the 16k versions.
There are currently known issues with loading modules from an old
loader as it can misalign them to load on a non-16k boundary.
Testing has shown good results in kernel workloads that allocate and
free large amounts of memory as only a quarter of the number of calls
into the VM subsystem are needed in the best case.
Reviewed by: markj
Tested by: gallatin
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34793
While merging this into CheriBSD (which has somewhat similar but conflicting
set of PV entry changes due to a different set of constants for PV entries)
it seems you did not correctly update places that check if a PV entry chunk
is full. For example, in get_pv_entry:
if (field < _NPCM) {
pv = &pc->pc_pventry[field * 64 + bit];
pc->pc_map[field] &= ~(1ul << bit);
/* If this was the last item, move it to tail */
=> if (pc->pc_map[0] == 0 && pc->pc_map[1] == 0 &&
=> pc->pc_map[2] == 0) {
TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
TAILQ_INSERT_TAIL(&pmap->pm_pvchunk, pc,
pc_list);
}
PV_STAT(atomic_add_long(&pv_entry_count, 1));
PV_STAT(atomic_subtract_int(&pv_entry_spare, 1));
return (pv);
That should presumably be comparing the entire pc_map[] to zero? (There
are two similar checks in pmap_pv_demote_l2 as well, one in a KASSERT)
I would suggest perhaps allocating a separate pc_fullmask[] array and
a PC_IS_FULL() wrapper that uses memcmp.
Btw, given that the compiler can inline memcmp against fixed-size const
arrays, it seems like you could just use the memcmp() version for PC_IS_FREE
always and avoid the #ifdef there.
--
John Baldwin
