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From: Alexander Motin <mav@FreeBSD.org>
Subject: git: 7eb023696a7d - stable/13 - coretemp(4): Switch to
smp_rendezvous_cpus().
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The branch stable/13 has been updated by mav:
URL: https://cgit.FreeBSD.org/src/commit/?id=7eb023696a7db1d66a811756b81e0cc7d617cc23
commit 7eb023696a7db1d66a811756b81e0cc7d617cc23
Author: Alexander Motin <mav@FreeBSD.org>
AuthorDate: 2021-07-30 03:16:22 +0000
Commit: Alexander Motin <mav@FreeBSD.org>
CommitDate: 2021-08-13 01:48:17 +0000
coretemp(4): Switch to smp_rendezvous_cpus().
Use of smp_rendezvous_cpus() instead of sched_bind() allows to not
block indefinitely if target CPU is running some thread with higher
priority, while all we need is single rdmsr/wrmsr instruction call.
I guess it should also be much cheaper than full thread migration.
MFC after: 2 weeks
Sponsored by: iXsystems, Inc.
(cherry picked from commit 74f80bc1af2ffd56ec290f610c80e46f768731a0)
---
sys/dev/coretemp/coretemp.c | 59 ++++++++++++++++++++++++++++-----------------
1 file changed, 37 insertions(+), 22 deletions(-)
diff --git a/sys/dev/coretemp/coretemp.c b/sys/dev/coretemp/coretemp.c
index 884ed6309f0e..53a2434254f6 100644
--- a/sys/dev/coretemp/coretemp.c
+++ b/sys/dev/coretemp/coretemp.c
@@ -42,7 +42,7 @@ __FBSDID("$FreeBSD$");
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/proc.h> /* for curthread */
-#include <sys/sched.h>
+#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
@@ -310,14 +310,32 @@ coretemp_detach(device_t dev)
return (0);
}
+struct coretemp_args {
+ u_int msr;
+ uint64_t val;
+};
+
+static void
+coretemp_rdmsr(void *arg)
+{
+ struct coretemp_args *args = arg;
+
+ args->val = rdmsr(args->msr);
+}
+
+static void
+coretemp_wrmsr(void *arg)
+{
+ struct coretemp_args *args = arg;
+
+ wrmsr(args->msr, args->val);
+}
+
static uint64_t
coretemp_get_thermal_msr(int cpu)
{
- uint64_t msr;
-
- thread_lock(curthread);
- sched_bind(curthread, cpu);
- thread_unlock(curthread);
+ struct coretemp_args args;
+ cpuset_t cpus;
/*
* The digital temperature reading is located at bit 16
@@ -329,27 +347,24 @@ coretemp_get_thermal_msr(int cpu)
* The temperature is computed by subtracting the temperature
* reading by Tj(max).
*/
- msr = rdmsr(MSR_THERM_STATUS);
-
- thread_lock(curthread);
- sched_unbind(curthread);
- thread_unlock(curthread);
-
- return (msr);
+ args.msr = MSR_THERM_STATUS;
+ CPU_SETOF(cpu, &cpus);
+ smp_rendezvous_cpus(cpus, smp_no_rendezvous_barrier, coretemp_rdmsr,
+ smp_no_rendezvous_barrier, &args);
+ return (args.val);
}
static void
coretemp_clear_thermal_msr(int cpu)
{
- thread_lock(curthread);
- sched_bind(curthread, cpu);
- thread_unlock(curthread);
-
- wrmsr(MSR_THERM_STATUS, 0);
-
- thread_lock(curthread);
- sched_unbind(curthread);
- thread_unlock(curthread);
+ struct coretemp_args args;
+ cpuset_t cpus;
+
+ args.msr = MSR_THERM_STATUS;
+ args.val = 0;
+ CPU_SETOF(cpu, &cpus);
+ smp_rendezvous_cpus(cpus, smp_no_rendezvous_barrier, coretemp_wrmsr,
+ smp_no_rendezvous_barrier, &args);
}
static int