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6ad7751537
Once the lazy preemption is supported, it would be desirable to change
the preemption models at runtime. So add support for dynamic preemption
using DYNAMIC_KEY.
::Tested lightly on Power10 LPAR
Performance numbers indicate that, preempt=none(no dynamic) and
preempt=none(dynamic) are close.
cat /sys/kernel/debug/sched/preempt
(none) voluntary full lazy
perf stat -e probe:__cond_resched -a sleep 1
Performance counter stats for 'system wide':
1,253 probe:__cond_resched
echo full > /sys/kernel/debug/sched/preempt
cat /sys/kernel/debug/sched/preempt
none voluntary (full) lazy
perf stat -e probe:__cond_resched -a sleep 1
Performance counter stats for 'system wide':
0 probe:__cond_resched
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250210184334.567383-2-sshegde@linux.ibm.com
17 lines
481 B
C
17 lines
481 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_POWERPC_PREEMPT_H
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#define __ASM_POWERPC_PREEMPT_H
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#include <asm-generic/preempt.h>
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#if defined(CONFIG_PREEMPT_DYNAMIC)
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#include <linux/jump_label.h>
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DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
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#define need_irq_preemption() \
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(static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched))
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#else
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#define need_irq_preemption() (IS_ENABLED(CONFIG_PREEMPTION))
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#endif
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#endif /* __ASM_POWERPC_PREEMPT_H */
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