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Date: Tue, 29 Aug 2017 11:46:39 +0000
From: Yang Zhang <yang.zhang.wz@...il.com>
To: linux-kernel@...r.kernel.org
Cc: kvm@...r.kernel.org, wanpeng.li@...mail.com, mst@...hat.com,
pbonzini@...hat.com, tglx@...utronix.de, rkrcmar@...hat.com,
dmatlack@...gle.com, agraf@...e.de, peterz@...radead.org,
linux-doc@...r.kernel.org, Yang Zhang <yang.zhang.wz@...il.com>,
Quan Xu <quan.xu0@...il.com>, Jonathan Corbet <corbet@....net>,
Jeremy Fitzhardinge <jeremy@...p.org>,
Chris Wright <chrisw@...s-sol.org>,
Alok Kataria <akataria@...are.com>,
Rusty Russell <rusty@...tcorp.com.au>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
"Luis R. Rodriguez" <mcgrof@...nel.org>,
Kees Cook <keescook@...omium.org>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Krzysztof Kozlowski <krzk@...nel.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Petr Mladek <pmladek@...e.com>, Jessica Yu <jeyu@...hat.com>,
Larry Finger <Larry.Finger@...inger.net>,
zijun_hu <zijun_hu@....com>, Baoquan He <bhe@...hat.com>,
Johannes Berg <johannes.berg@...el.com>,
Ian Abbott <abbotti@....co.uk>,
virtualization@...ts.linux-foundation.org,
linux-fsdevel@...r.kernel.org
Subject: [RFC PATCH v2 5/7] Documentation: Add three sysctls for smart idle poll
To reduce the cost of poll, we introduce three sysctl to control the
poll time.
Signed-off-by: Yang Zhang <yang.zhang.wz@...il.com>
Signed-off-by: Quan Xu <quan.xu0@...il.com>
Cc: Jonathan Corbet <corbet@....net>
Cc: Jeremy Fitzhardinge <jeremy@...p.org>
Cc: Chris Wright <chrisw@...s-sol.org>
Cc: Alok Kataria <akataria@...are.com>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
Cc: "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc: Kees Cook <keescook@...omium.org>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Petr Mladek <pmladek@...e.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Jessica Yu <jeyu@...hat.com>
Cc: Larry Finger <Larry.Finger@...inger.net>
Cc: zijun_hu <zijun_hu@....com>
Cc: Baoquan He <bhe@...hat.com>
Cc: Johannes Berg <johannes.berg@...el.com>
Cc: Ian Abbott <abbotti@....co.uk>
Cc: linux-doc@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Cc: virtualization@...ts.linux-foundation.org
Cc: linux-fsdevel@...r.kernel.org
---
Documentation/sysctl/kernel.txt | 25 +++++++++++++++++++++++++
arch/x86/kernel/paravirt.c | 4 ++++
include/linux/kernel.h | 6 ++++++
kernel/sysctl.c | 23 +++++++++++++++++++++++
4 files changed, 58 insertions(+)
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index bac23c1..67447b8 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -63,6 +63,9 @@ show up in /proc/sys/kernel:
- perf_event_max_stack
- perf_event_max_contexts_per_stack
- pid_max
+- poll_grow [ X86 only ]
+- poll_shrink [ X86 only ]
+- poll_threshold_ns [ X86 only ]
- powersave-nap [ PPC only ]
- printk
- printk_delay
@@ -702,6 +705,28 @@ kernel tries to allocate a number starting from this one.
==============================================================
+poll_grow: (X86 only)
+
+This parameter is multiplied in the grow_poll_ns() to increase the poll time.
+By default, the values is 2.
+
+==============================================================
+poll_shrink: (X86 only)
+
+This parameter is divided in the shrink_poll_ns() to reduce the poll time.
+By default, the values is 2.
+
+==============================================================
+poll_threshold_ns: (X86 only)
+
+This parameter controls the max poll time before entering real idle path.
+This parameter is expected to take effect only when running inside a VM.
+It would make no sense to turn on it in bare mental.
+By default, the values is 0 means don't poll. It is recommended to change
+the value to non-zero if running latency-bound workloads inside VM.
+
+==============================================================
+
powersave-nap: (PPC only)
If set, Linux-PPC will use the 'nap' mode of powersaving,
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index a11b2c2..0b92f8f 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -318,6 +318,10 @@ struct pv_idle_ops pv_idle_ops = {
.update = paravirt_nop,
};
+unsigned long poll_threshold_ns;
+unsigned int poll_shrink = 2;
+unsigned int poll_grow = 2;
+
__visible struct pv_irq_ops pv_irq_ops = {
.save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
.restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index bd6d96c..6cb2820 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -462,6 +462,12 @@ extern __scanf(2, 0)
extern bool crash_kexec_post_notifiers;
+#ifdef CONFIG_PARAVIRT
+extern unsigned long poll_threshold_ns;
+extern unsigned int poll_shrink;
+extern unsigned int poll_grow;
+#endif
+
/*
* panic_cpu is used for synchronizing panic() and crash_kexec() execution. It
* holds a CPU number which is executing panic() currently. A value of
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 6648fbb..9b86a8f 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1229,6 +1229,29 @@ static int sysrq_sysctl_handler(struct ctl_table *table, int write,
.extra2 = &one,
},
#endif
+#ifdef CONFIG_PARAVIRT
+ {
+ .procname = "halt_poll_threshold",
+ .data = &poll_threshold_ns,
+ .maxlen = sizeof(unsigned long),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+ {
+ .procname = "halt_poll_grow",
+ .data = &poll_grow,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+ {
+ .procname = "halt_poll_shrink",
+ .data = &poll_shrink,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+#endif
{ }
};
--
1.8.3.1
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