Module Name: src
Committed By: martin
Date: Sat Sep 21 12:20:23 UTC 2024
Modified Files:
src/sys/arch/amd64/amd64 [netbsd-10]: db_interface.c
src/sys/arch/i386/i386 [netbsd-10]: db_interface.c
Log Message:
Pull up following revision(s) (requested by rin in ticket #900):
sys/arch/amd64/amd64/db_interface.c: revision 1.42
sys/arch/i386/i386/db_interface.c: revision 1.89
when cpus are paused (spinning) in DDB, call x86_pause() in the loop,
hopefully this can reduce power usage while doing nothing.
ok chs@
XXX: apply to i386
i386: DDB: Call x86_pause() (`pause` insn) when CPUs are paused
as already done for amd64:
https://mail-index.netbsd.org/source-changes/2023/07/31/msg146423.html
`pause` insn has been introduced to Pentium 4. However, its opcode is
consisted of `nop` (0x90) followed by `rep` prefix (0xf3), and therefore
interpreted as `nop` for older processors. Intel assured this behavior [1].
Also note that we already use `pause` unconditionally for i386.
Briefly tested on QEMU.
[1] Intel, ``AP-949 Using Spin-Loops on Intel Pentium 4 Processor and
Intel Xeon Processor'', Version 2.1, Sec 2.1.1. (2001)
To generate a diff of this commit:
cvs rdiff -u -r1.41 -r1.41.2.1 src/sys/arch/amd64/amd64/db_interface.c
cvs rdiff -u -r1.88 -r1.88.2.1 src/sys/arch/i386/i386/db_interface.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/amd64/amd64/db_interface.c
diff -u src/sys/arch/amd64/amd64/db_interface.c:1.41 src/sys/arch/amd64/amd64/db_interface.c:1.41.2.1
--- src/sys/arch/amd64/amd64/db_interface.c:1.41 Wed Oct 26 23:38:06 2022
+++ src/sys/arch/amd64/amd64/db_interface.c Sat Sep 21 12:20:22 2024
@@ -1,4 +1,4 @@
-/* $NetBSD: db_interface.c,v 1.41 2022/10/26 23:38:06 riastradh Exp $ */
+/* $NetBSD: db_interface.c,v 1.41.2.1 2024/09/21 12:20:22 martin Exp $ */
/*
* Mach Operating System
@@ -33,7 +33,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: db_interface.c,v 1.41 2022/10/26 23:38:06 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: db_interface.c,v 1.41.2.1 2024/09/21 12:20:22 martin Exp $");
#include "opt_ddb.h"
#include "opt_multiprocessor.h"
@@ -303,7 +303,7 @@ ddb_suspend(struct trapframe *frame)
atomic_or_32(&ci->ci_flags, CPUF_PAUSE);
while (ci->ci_flags & CPUF_PAUSE)
- ;
+ x86_pause();
ci->ci_ddb_regs = 0;
tlbflushg();
}
Index: src/sys/arch/i386/i386/db_interface.c
diff -u src/sys/arch/i386/i386/db_interface.c:1.88 src/sys/arch/i386/i386/db_interface.c:1.88.2.1
--- src/sys/arch/i386/i386/db_interface.c:1.88 Wed Oct 26 23:38:07 2022
+++ src/sys/arch/i386/i386/db_interface.c Sat Sep 21 12:20:23 2024
@@ -1,4 +1,4 @@
-/* $NetBSD: db_interface.c,v 1.88 2022/10/26 23:38:07 riastradh Exp $ */
+/* $NetBSD: db_interface.c,v 1.88.2.1 2024/09/21 12:20:23 martin Exp $ */
/*
* Mach Operating System
@@ -33,7 +33,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: db_interface.c,v 1.88 2022/10/26 23:38:07 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: db_interface.c,v 1.88.2.1 2024/09/21 12:20:23 martin Exp $");
#include "opt_ddb.h"
#include "opt_multiprocessor.h"
@@ -369,7 +369,7 @@ ddb_suspend(struct trapframe *frame)
atomic_or_32(&ci->ci_flags, CPUF_PAUSE);
while (ci->ci_flags & CPUF_PAUSE)
- ;
+ x86_pause();
ci->ci_ddb_regs = 0;
tlbflushg();
}
