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diff --git a/lib/libc/sys/_umtx_op.2 b/lib/libc/sys/_umtx_op.2
--- a/lib/libc/sys/_umtx_op.2
+++ b/lib/libc/sys/_umtx_op.2
@@ -1270,6 +1270,17 @@
See
.Sx ROBUST UMUTEXES
subsection for details.
+.It Dv UMTX_OP_GET_MIN_TIMEOUT
+Writes out the current value of minimal umtx operations timeout,
+in nanoseconds, into the long integer variable pointed to by
+.Fa uaddr1 .
+.It Dv UMTX_OP_SET_MIN_TIMEOUT
+Set the minimal amount of time, in nanoseconds, the thread is required
+to sleep for umtx operations specifying a timeout using absolute clocks.
+The value is taken from the
+.Fa val
+argument of the call.
+Zero means no minimum.
.El
.Pp
The
diff --git a/lib/libthr/libthr.3 b/lib/libthr/libthr.3
--- a/lib/libthr/libthr.3
+++ b/lib/libthr/libthr.3
@@ -196,6 +196,12 @@
threads are inserted at the head of the sleep queue, instead of its tail.
Bigger values reduce the frequency of the FIFO discipline.
The value must be between 0 and 255.
+.It Dv LIBPTHREAD_UMTX_MIN_TIMEOUT
+The minimal amount of time, in nanoseconds, the thread is required to sleep
+for pthread operations specifying a timeout.
+If the operation requests a timeout less than the value provided,
+it is silently increased to the value.
+The value of zero means no minimum (default).
.Pp
.El
The following
diff --git a/lib/libthr/thread/thr_init.c b/lib/libthr/thread/thr_init.c
--- a/lib/libthr/thread/thr_init.c
+++ b/lib/libthr/thread/thr_init.c
@@ -522,6 +522,17 @@
if (env)
_thr_queuefifo = atoi(env);
TAILQ_INIT(&_thr_atfork_list);
+ env = getenv("LIBPTHREAD_UMTX_MIN_TIMEOUT");
+ if (env) {
+ char *endptr;
+ long mint;
+
+ mint = strtol(env, &endptr, 0);
+ if (*endptr == '\0' && mint >= 0) {
+ _umtx_op(NULL, UMTX_OP_SET_MIN_TIMEOUT,
+ mint, NULL, NULL);
+ }
+ }
}
init_once = 1;
}
diff --git a/sys/kern/kern_thread.c b/sys/kern/kern_thread.c
--- a/sys/kern/kern_thread.c
+++ b/sys/kern/kern_thread.c
@@ -101,7 +101,7 @@
"struct proc KBI p_filemon");
_Static_assert(offsetof(struct proc, p_comm) == 0x3e0,
"struct proc KBI p_comm");
-_Static_assert(offsetof(struct proc, p_emuldata) == 0x4c8,
+_Static_assert(offsetof(struct proc, p_emuldata) == 0x4d0,
"struct proc KBI p_emuldata");
#endif
#ifdef __i386__
@@ -121,7 +121,7 @@
"struct proc KBI p_filemon");
_Static_assert(offsetof(struct proc, p_comm) == 0x284,
"struct proc KBI p_comm");
-_Static_assert(offsetof(struct proc, p_emuldata) == 0x310,
+_Static_assert(offsetof(struct proc, p_emuldata) == 0x318,
"struct proc KBI p_emuldata");
#endif
diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c
--- a/sys/kern/kern_umtx.c
+++ b/sys/kern/kern_umtx.c
@@ -700,6 +700,19 @@
(umtxtime->_flags & UMTX_ABSTIME) != 0, &umtxtime->_timeout);
}
+static void
+umtx_abs_timeout_enforce_min(sbintime_t *sbt)
+{
+ sbintime_t when, mint;
+
+ mint = curproc->p_umtx_min_timeout;
+ if (__predict_false(mint != 0)) {
+ when = sbinuptime() + mint;
+ if (*sbt < when)
+ *sbt = when;
+ }
+}
+
static int
umtx_abs_timeout_getsbt(struct umtx_abs_timeout *timo, sbintime_t *sbt,
int *flags)
@@ -739,6 +752,7 @@
return (0);
}
*sbt = bttosbt(bt);
+ umtx_abs_timeout_enforce_min(sbt);
/*
* Check if the absolute time should be aligned to
@@ -4594,6 +4608,33 @@
return (0);
}
+static int
+__umtx_op_get_min_timeout(struct thread *td, struct _umtx_op_args *uap,
+ const struct umtx_copyops *ops)
+{
+ long val;
+ int error, val1;
+
+ val = sbttons(td->td_proc->p_umtx_min_timeout);
+ if (ops->compat32) {
+ val1 = (int)val;
+ error = copyout(&val1, uap->uaddr1, sizeof(val1));
+ } else {
+ error = copyout(&val, uap->uaddr1, sizeof(val));
+ }
+ return (error);
+}
+
+static int
+__umtx_op_set_min_timeout(struct thread *td, struct _umtx_op_args *uap,
+ const struct umtx_copyops *ops)
+{
+ if (uap->val < 0)
+ return (EINVAL);
+ td->td_proc->p_umtx_min_timeout = nstosbt(uap->val);
+ return (0);
+}
+
#if defined(__i386__) || defined(__amd64__)
/*
* Provide the standard 32-bit definitions for x86, since native/compat32 use a
@@ -4816,6 +4857,8 @@
[UMTX_OP_SEM2_WAKE] = __umtx_op_sem2_wake,
[UMTX_OP_SHM] = __umtx_op_shm,
[UMTX_OP_ROBUST_LISTS] = __umtx_op_robust_lists,
+ [UMTX_OP_GET_MIN_TIMEOUT] = __umtx_op_get_min_timeout,
+ [UMTX_OP_SET_MIN_TIMEOUT] = __umtx_op_set_min_timeout,
};
static const struct umtx_copyops umtx_native_ops = {
@@ -4990,6 +5033,8 @@
umtx_thread_cleanup(td);
td->td_rb_list = td->td_rbp_list = td->td_rb_inact = 0;
}
+
+ p->p_umtx_min_timeout = 0;
}
/*
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -741,6 +741,7 @@
uint64_t p_elf_flags; /* (x) ELF flags */
void *p_elf_brandinfo; /* (x) Elf_Brandinfo, NULL for
non ELF binaries. */
+ sbintime_t p_umtx_min_timeout;
/* End area that is copied on creation. */
#define p_endcopy p_xexit
diff --git a/sys/sys/umtx.h b/sys/sys/umtx.h
--- a/sys/sys/umtx.h
+++ b/sys/sys/umtx.h
@@ -103,6 +103,8 @@
#define UMTX_OP_SEM2_WAKE 24
#define UMTX_OP_SHM 25
#define UMTX_OP_ROBUST_LISTS 26
+#define UMTX_OP_GET_MIN_TIMEOUT 27
+#define UMTX_OP_SET_MIN_TIMEOUT 28
/*
* Flags for ops; the double-underbar convention must be maintained for future

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