Re: [PATCH v3 4/4] arm64: support batched/deferred tlb shootdown during page reclamation
From: Nadav Amit <hidden>
Date: 2022-09-15 14:31:54
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On Sep 14, 2022, at 11:42 PM, Barry Song [off-list ref] wrote:quoted
The very idea behind TLB deferral is the opportunity it (might) provide to accumulate address ranges and cpu masks so that individual TLB flush can be replaced with a more cost effective range based TLB flush. Hence I guess unless address range or cpumask based cost effective TLB flush is available, deferral does not improve the unmap performance as much.After sending tlbi, if we wait for the completion of tlbi, we have to get Ack from all cpus in the system, tlbi is not scalable. The point here is that we avoid waiting for each individual TLBi. Alternatively, they are batched. If you read the benchmark in the commit log, you can find the great decline in the cost to swap out a page.
Just a minor correction: arch_tlbbatch_flush() does not collect ranges. On x86 it only accumulate CPU mask. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel