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Don't run sched_preempt() inside of an extra critical section. This disables

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the sched_preempt() switch optimization and causes the sched lock to be dropped
and immediately reacquired.

Reviewed by:	jhb, kib, mav, markj (with changes)
Differential Revision:	https://reviews.freebsd.org/D22623
This commit is contained in:
Jeff Roberson 2019-12-02 22:34:19 +00:00
parent eaad2b87d9
commit fb6a57ef89
1 changed files with 10 additions and 8 deletions
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18
sys/x86/x86/mp_x86.c
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@ -1261,18 +1261,11 @@ ipi_bitmap_handler(struct trapframe frame)
int cpu = PCPU_GET(cpuid);
u_int ipi_bitmap;
critical_enter();
td = curthread;
td->td_intr_nesting_level++;
oldframe = td->td_intr_frame;
td->td_intr_frame = &frame;
ipi_bitmap = atomic_readandclear_int(&cpuid_to_pcpu[cpu]->pc_ipi_bitmap);
if (ipi_bitmap & (1 << IPI_PREEMPT)) {
#ifdef COUNT_IPIS
(*ipi_preempt_counts[cpu])++;
#endif
sched_preempt(td);
}
if (ipi_bitmap & (1 << IPI_AST)) {
#ifdef COUNT_IPIS
(*ipi_ast_counts[cpu])++;
@ -1280,14 +1273,23 @@ ipi_bitmap_handler(struct trapframe frame)
/* Nothing to do for AST */
}
if (ipi_bitmap & (1 << IPI_HARDCLOCK)) {
critical_enter();
#ifdef COUNT_IPIS
(*ipi_hardclock_counts[cpu])++;
#endif
hardclockintr();
critical_exit();
}
/* Run preempt after clock handlers since it may switch. */
if (ipi_bitmap & (1 << IPI_PREEMPT)) {
#ifdef COUNT_IPIS
(*ipi_preempt_counts[cpu])++;
#endif
sched_preempt(td);
}
td->td_intr_frame = oldframe;
td->td_intr_nesting_level--;
critical_exit();
}
/*