virtual memory reservation and a private pool of memory pages -- by a scheme
based on memory pools.
This allows better utilization of memory because buffers can now be allocated
with a granularity finer than the system's native page size (useful for
filesystems with e.g. 1k or 2k fragment sizes). It also avoids fragmentation
of virtual to physical memory mappings (due to the former fixed virtual
address reservation) resulting in better utilization of MMU resources on some
platforms. Finally, the scheme is more flexible by allowing run-time decisions
on the amount of memory to be used for buffers.
On the other hand, the effectiveness of the LRU queue for buffer recycling
may be somewhat reduced compared to the traditional method since, due to the
nature of the pool based memory allocation, the actual least recently used
buffer may release its memory to a pool different from the one needed by a
newly allocated buffer. However, this effect will kick in only if the
system is under memory pressure.
timeout()/untimeout() API:
- Clients supply callout handle storage, thus eliminating problems of
resource allocation.
- Insertion and removal of callouts is constant time, important as
this facility is used quite a lot in the kernel.
The old timeout()/untimeout() API has been removed from the kernel.
conf/param.c, and move the initialisation of the sb_max
variable from kern/uipc_socket2.c to conf/param.c. Now
everthing that includes sys/socketvar.h doesn't get
recompiled when SB_MAX's value changes.
(2x NPROC plus slop) unless expclitly set. Use current constant value
(100) as a lower bound, as suggested by Chuck Cranor.
Move NPROC and other parameter definitions from param.c to param.h so
they are visible to vm/vm_map.h.
Systems with hand-tuned NPROC should now support that many processes.
UVM was written by chuck cranor <chuck@maria.wustl.edu>, with some
minor portions derived from the old Mach code. i provided some help
getting swap and paging working, and other bug fixes/ideas. chuck
silvers <chuq@chuq.com> also provided some other fixes.
this is the rest of the MI portion changes.
this will be KNF'd shortly. :-)
Add code to netstat to use libkvm to for kernel variables "mclbytes"
and "msize', and if found, use those for netstat -m rather than
compiled-in defaults.
Eliminate obsolete global kernel variable "struct timezone tz"
Add RTC_OFFSET option
Add global kernel variable rtc_offset, which is initialized by
RTC_OFFSET at kernel compile time.
on i386, x68k, mac68k, pc532 and arm32, RTC_OFFSET indicates how many
minutes west (east) of GMT the hardware RTC runs. Defaults to 0.
Places where tz variable was used to indicate this in the past have
been replaced with rtc_offset.
Add sysctl interface to rtc_offset.
Kill obsolete DST_* macros in sys/time.h
gettimeofday now always returns zeroed timezone if zone is requested.
settimeofday now ignores and logs attempts to set non-existant kernel
timezone.
christos