From: Stuart Henderson <stu@spacehopper.org>
Subject: btrace, identifying syscall+0x5c4
To: tech <tech@openbsd.org>
Date: Mon, 2 Dec 2024 13:53:02 +0000

Thought I'd take a look at a kernel profile from a machine which is
fairly "interesting" in terms of kernel spin. (Running -current).

In the attached output from running "btrace kprofile.bt" I have a
lot of time accounted for under syscall+0x5c4, which has _kernel_lock
directly next to it in the traces, and I was wondering what that is.
Bit confused by disasm of trap.o but my guess is that it might be
a lock relating to dt(4) itself, is that right?