implementation:
-don't return a difference, this can overflow
-don't try to substract typed pointers which don't belong to the
same object, this gives undefined results
This fixes instabilities of programs which use more than a handful
of threads, eg spuriously failing pthread_join().
XXX This must not be enabled by default because the LWP private mechanism
is reserved for TLS. It is provided only as a test/demo.
XXX Since ucontext_t does not contain the thread private variable, for a
short time after threads are created their thread specific data is unset.
If a signal arrives during that time we are screwed.
- No longer need pthread__osrev.
- Rearrange _lwp_ctl() calls slightly.
address space available to processes. this limit exists in most other
modern unix variants, and like most of them, our defaults are unlimited.
remove the old mmap / rlimit.datasize hack.
- adds the VMCMD_STACK flag to all the stack-creation vmcmd callers.
it is currently unused, but was added a few years ago.
- add a pair of new process size values to kinfo_proc2{}. one is the
total size of the process memory map, and the other is the total size
adjusted for unused stack space (since most processes have a lot of
this...)
- patch sh, and csh to notice RLIMIT_AS. (in some cases, the alias
RLIMIT_VMEM was already present and used if availble.)
- patch ps, top and systat to notice the new k_vm_vsize member of
kinfo_proc2{}.
- update irix, svr4, svr4_32, linux and osf1 emulations to support
this information. (freebsd could be done, but that it's best left
as part of the full-update of compat/freebsd.)
this addresses PR 7897. it also gives correct memory usage values,
which have never been entirely correct (since mmap), and have been
very incorrect since jemalloc() was enabled.
tested on i386 and sparc64, build tested on several other platforms.
thanks to many folks for feedback and testing but most espcially
chuq and yamt for critical suggestions that lead to this patch not
having a special ugliness i wasn't happy with anyway :-)
piece of historical behavior, not a current bug. Also, while here, add a
bit about disk write-back caches and point to dkctl/scsictl.
Bump date. (first time since 1993!)
