Note that ULong in this code is actually defined as an unsigned integer across
all arches so that the gdtoa() function always processes 32 bit data
despite the unfortunate naming of "ULong".
libraries had not had their versions bumped relative to 6.3-REL but
had indeed been changed. We need to bump their version so they can be
properly added to the compat6x port:
libasn1.so.8 libgssapi.so.8 libhdb.so.8 libkadm5clnt.so.8
libkadm5srv.so.8 libkafs5.so.8 libkrb5.so.8 libobjc.so.2
MFC After: 1 day
doesn't use the default CFLAGS which contain -fno-strict-aliasing.
Until the code is cleaned up, just add -fno-strict-aliasing to the
CFLAGS of these for the tinderboxes' sake, allowing the rest of the
tree to have -Werror enabled again.
cause the build to fail because y.tab.c can have a more
recent modification time than y.tab.h, and the bad rule
relied on the opposite.
(The last write to y.tab.c by yacc(1) happens after the
last write to y.tab.h, according to truss(1).)
Reported by: kensmith
fixes a NULL-dereference of curthread when libstdc+ initializes
the exception handling globals on archs we can't use GNU TLS due
to lack of support in binutils 2.15 (i.e. arm and sparc64), yet,
thus making threaded C++ programs compiled with GCC 4.2.1 work
again on these archs.
Reviewed by: davidxu
MFC after: 3 days
to tune pthread mutex performance:
1. LIBPTHREAD_SPINLOOPS
If a pthread mutex is being locked by another thread, this environment
variable sets total number of spin loops before the current thread
sleeps in kernel, this saves a syscall overhead if the mutex will be
unlocked very soon (well written application code).
2. LIBPTHREAD_YIELDLOOPS
If a pthread mutex is being locked by other threads, this environment
variable sets total number of sched_yield() loops before the currrent
thread sleeps in kernel. if a pthread mutex is locked, the current thread
gives up cpu, but will not sleep in kernel, this means, current thread
does not set contention bit in mutex, but let lock owner to run again
if the owner is on kernel's run queue, and when lock owner unlocks the
mutex, it does not need to enter kernel and do lots of work to resume
mutex waiters, in some cases, this saves lots of syscall overheads for
mutex owner.
In my practice, sometimes LIBPTHREAD_YIELDLOOPS can massively improve performance
than LIBPTHREAD_SPINLOOPS, this depends on application. These two environments
are global to all pthread mutex, there is no interface to set them for each
pthread mutex, the default values are zero, this means spinning is turned off
by default.
is also implemented in glibc and is used by a number of existing
applications (mysql, firefox, etc).
This mutex type is a default mutex with the additional property that
it spins briefly when attempting to acquire a contested lock, doing
trylock operations in userland before entering the kernel to block if
eventually unsuccessful.
The expectation is that applications requesting this mutex type know
that the mutex is likely to be only held for very brief periods, so it
is faster to spin in userland and probably succeed in acquiring the
mutex, than to enter the kernel and sleep, only to be woken up almost
immediately. This can help significantly in certain cases when
pthread mutexes are heavily contended and held for brief durations
(such as mysql).
Spin up to 200 times before entering the kernel, which represents only
a few us on modern CPUs. No performance degradation was observed with
this value and it is sufficient to avoid a large performance drop in
mysql performance in the heavily contended pthread mutex case.
The libkse implementation is a NOP.
Reviewed by: jeff
MFC after: 3 days
This can only happen on 32-bit systems when you're reading
an uncompressed archive and the skip request is an exact
multiple of 4G (e.g., skipping a tar entry with an 8G body).
The symptom is that the read_ahead() ends up returning zero
bytes, and the extraction stops with a premature end-of-file.
Using '1' here is more correct anyway, as it allows read_ahead()
to function opportunistically and minimize copying.
MFC after: 5 days
