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The sched_add() function is not only used when the thread is initially

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started, but also by the turnstiles to mark a thread as runnable for
all locks, for instance sleepqueues do:
setrunnable()->sched_wakeup()->sched_add()

In r326218 code was added to allow booting from non-zero CPU numbers
by setting the ts_cpu field inside the ULE scheduler's sched_add()
function. This had an undesired side-effect that prior sched_pin() and
sched_bind() calls got disregarded. This patch fixes the
initialization of the ts_cpu field for the ULE scheduler to only
happen once when the initial thread is constructed during system
init. Forking will then later on ensure that a valid ts_cpu value gets
copied to all children.

Reviewed by:	jhb, kib
Discussed with:	nwhitehorn
MFC after:	1 month
Differential revision:	https://reviews.freebsd.org/D13298
Sponsored by:	Mellanox Technologies
This commit is contained in:
Hans Petter Selasky 2017-11-29 23:28:40 +00:00
parent 97a4e58919
commit 1408b84a26
1 changed files with 1 additions and 2 deletions
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3
sys/kern/sched_ule.c
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@ -1405,7 +1405,6 @@ sched_setup(void *dummy)
/* Add thread0's load since it's running. */
TDQ_LOCK(tdq);
td_get_sched(&thread0)->ts_cpu = curcpu; /* Something valid to start */
thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF());
tdq_load_add(tdq, &thread0);
tdq->tdq_lowpri = thread0.td_priority;
@ -1642,6 +1641,7 @@ schedinit(void)
ts0->ts_ltick = ticks;
ts0->ts_ftick = ticks;
ts0->ts_slice = 0;
ts0->ts_cpu = curcpu; /* set valid CPU number */
}
/*
@ -2453,7 +2453,6 @@ sched_add(struct thread *td, int flags)
* Pick the destination cpu and if it isn't ours transfer to the
* target cpu.
*/
td_get_sched(td)->ts_cpu = curcpu; /* Pick something valid to start */
cpu = sched_pickcpu(td, flags);
tdq = sched_setcpu(td, cpu, flags);
tdq_add(tdq, td, flags);