CONFIG_DEBUG_TLBFLUSH: Set upper limit of TLB entries to flush one-by-one

General informations

The Linux kernel configuration item CONFIG_DEBUG_TLBFLUSH:

• prompt: Set upper limit of TLB entries to flush one-by-one
• type: bool
• depends on: CONFIG_DEBUG_KERNEL
• defined in arch/x86/Kconfig.debug
• found in Linux kernels: 3.6–3.19, 4.0–4.20, 5.0–5.19, 6.0–6.12, 6.13-rc+HEAD

Help text

X86-only for now.

This option allows the user to tune the amount of TLB entries the kernel flushes one-by-one instead of doing a full TLB flush. In certain situations, the former is cheaper. This is controlled by the tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it to -1, the code flushes the whole TLB unconditionally. Otherwise, for positive values of it, the kernel will use single TLB entry invalidating instructions according to the following formula:

flush_entries <= active_tlb_entries / 2^tlb_flushall_shift

If in doubt, say "N".

Hardware

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This page is automaticly generated with free (libre, open) software lkddb(see lkddb-sources).

The data is retrived from:

• Linux kernel
• Linux Kernel Driver DataBase (LKDDb)

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