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[v10,05/11] arm64: add support for poll_idle()

Message ID 20250218213337.377987-6-ankur.a.arora@oracle.com (mailing list archive)
State New
Headers show
Series arm64: support poll_idle() | expand

Commit Message

Ankur Arora Feb. 18, 2025, 9:33 p.m. UTC 
Polling in idle helps reduce the cost of remote wakeups: if the target
sets TIF_POLLING_NRFLAG (as it does while polling in idle), the scheduler
can do remote wakeups just by setting the TIF_NEED_RESCHED.

This contrasts with sending an IPI, and incurring the cost of handling
the cost of the interrupt on the receiver.

Enabling poll_idle() needs a cheap mechanism to do the actual polling
(via smp_cond_load_relaxed_timewait()) and TIF_POLLING_NRFLAG support.

arm64 has both of these. So, select ARCH_HAS_OPTIMIZED_POLL.

Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
---
 arch/arm64/Kconfig | 1 +
 1 file changed, 1 insertion(+)
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Patch

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 100570a048c5..d96a6c6d8894 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -39,6 +39,7 @@  config ARM64
 	select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
 	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 	select ARCH_HAS_NONLEAF_PMD_YOUNG if ARM64_HAFT
+	select ARCH_HAS_OPTIMIZED_POLL
 	select ARCH_HAS_PTE_DEVMAP
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_HW_PTE_YOUNG