[PATCH RFC v2 08/15] bpf, x86: Maintain Tasks RCU trampoline nesting in the BPF trampoline
David Laight
david.laight.linux at gmail.com
Sat Sep 12 14:14:00 PDT 2026
On Sat, 12 Sep 2026 11:03:34 -0700
"Paul E. McKenney" <paulmck at kernel.org> wrote:
> In the old kernels, yes, we have current->trc_reader_nesting++.
> In the newer kernels, Tasks Trace RCU is instead implemented in terms
> of SRCU-fast, which instead increments per-CPU counters. Which among
> other thins is a bit faster and does not need to hook into the scheduler.
Isn't that rather architecture dependant?
It is fine on x86, but on arm incrementing a per-cpu variable is
significantly expensive.
David
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