K 10
svn:author
V 5
markj
K 8
svn:date
V 27
2019-02-25T19:22:13.375299Z
K 7
svn:log
V 1069
Improve vmem tuning for platforms without a direct map.

On platforms without a direct map (i.e., platforms without
UMA_MD_SMALL_ALLOC defined), the boundary tag allocator reserves a
number of tags for use when allocating a new slab of boundary tags,
as such platforms require free boundary tags in order to allocate
boundary tags.  r327899 increased the number of boundary tags required
for a KVA allocation in the worst case, and the aforementioned
reservation was not updated accordingly.  In some cases, this could
lead to a system hang.  Fix the problem by increasing this reservation.

Also reduce KVA_QUANTUM on systems lacking superpage support.
The previous import quantum (4MB with a 4KB page size) was quite large
for systems with limited KVA, and fragmentation in kernel_arena could
cause kernel memory allocation failures even with a substantial amount
of free KVA.

Reported and tested by:	jhibbits
Reviewed by:	alc, kib
No objections:	jeff
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D19337

END