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Date: Sat, 25 Jun 2022 08:12:09 +0900
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From: Akira Yokosawa <akiyks@gmail.com>
Subject: =?UTF-8?Q?=5bperfbook=5d_Analogy_of_Figure_7=2e11_Locking_=e2=80=9c?=
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To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: perfbook@vger.kernel.org, Akira Yokosawa <akiyks@gmail.com>
List-ID: <perfbook.vger.kernel.org>

Hi Paul,

I find the analogy of Figure 7.11 hard to grasp.

Whether a lock is global or per-instance, the cost of locking
(saw kerf) is observed only when a CPU/thread does the locking
operation.

In this figure, does each board represent data elements, not a
CPU/thread?  If this is the case, what does the waste of "saw kerf"
mean?

What am I missing?

(I hope I am clear enough on what I don't get...)

        Thanks, Akira