Re: [PATCH] Documentation/features: mark BATCHED_UNMAP_TLB_FLUSH doesn't apply to ARM64
From: Anshuman Khandual <hidden>
Date: 2021-02-23 06:11:04
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linux-arm-kernel, linux-doc, lkml
On 2/23/21 6:02 AM, Barry Song wrote:
BATCHED_UNMAP_TLB_FLUSH is used on x86 to do batched tlb shootdown by sending one IPI to TLB flush all entries after unmapping pages rather than sending an IPI to flush each individual entry. On arm64, tlb shootdown is done by hardware. Flush instructions are innershareable. The local flushes are limited to the boot (1 per CPU) and when a task is getting a new ASID.
Is there any previous discussion around this ?
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So marking this feature as "TODO" is not proper. ".." isn't good as well. So this patch adds a "N/A" for this kind of features which are not needed on some architectures. Cc: Mel Gorman <mgorman@suse.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Barry Song <redacted> --- Documentation/features/arch-support.txt | 1 + Documentation/features/vm/TLB/arch-support.txt | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-)diff --git a/Documentation/features/arch-support.txt b/Documentation/features/arch-support.txt index d22a1095e661..118ae031840b 100644 --- a/Documentation/features/arch-support.txt +++ b/Documentation/features/arch-support.txt@@ -8,4 +8,5 @@ The meaning of entries in the tables is: | ok | # feature supported by the architecture |TODO| # feature not yet supported by the architecture | .. | # feature cannot be supported by the hardware + | N/A| # feature doesn't apply to the architecture
NA might be better here. s/doesn't apply/not applicable/ in order to match NA. Still wondering if NA is really needed when there is already ".." ? Regardless either way should be fine.
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diff --git a/Documentation/features/vm/TLB/arch-support.txt b/Documentation/features/vm/TLB/arch-support.txt index 30f75a79ce01..0d070f9f98d8 100644 --- a/Documentation/features/vm/TLB/arch-support.txt +++ b/Documentation/features/vm/TLB/arch-support.txt@@ -9,7 +9,7 @@ | alpha: | TODO | | arc: | TODO | | arm: | TODO | - | arm64: | TODO | + | arm64: | N/A | | c6x: | .. | | csky: | TODO | | h8300: | .. |