From: Thomas Gleixner <tglx@linutronix.de>
To: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Wanpeng Li <kernellwp@gmail.com>, Ingo Molnar <mingo@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
the arch/x86 maintainers <x86@kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
tony.luck@intel.com, Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
mchehab@kernel.org, Andrew Morton <akpm@linux-foundation.org>,
krzk@kernel.org, jpoimboe@redhat.com,
Andy Lutomirski <luto@kernel.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Thomas Garnier <thgarnie@google.com>,
Robert Gerst <rgerst@gmail.com>,
Mathias Krause <minipli@googlemail.com>,
douly.fnst@cn.fujitsu.com, Nicolai Stange <nicstange@gmail.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
dvlasenk@redhat.com,
Daniel Bristot de Oliveira <bristot@redhat.com>,
yamada.masahiro@socionext.com, mika.westerberg@linux.intel.com,
Chen Yu <yu.c.chen@intel.com>,
aaron.lu@intel.com, Steven Rostedt <rostedt@goodmis.org>,
Kyle Huey <me@kylehuey.com>, Len Brown <len.brown@intel.com>,
Prarit Bhargava <prarit@redhat.com>,
hidehiro.kawai.ez@hitachi.com, fengtiantian@huawei.com,
pmladek@suse.com, jeyu@redhat.com, Larry.Finger@lwfinger.net,
zijun_hu@htc.com, luisbg@osg.samsung.com,
johannes.berg@intel.com, niklas.soderlund+renesas@ragnatech.se,
zlpnobody@gmail.com, Alexey Dobriyan <adobriyan@gmail.com>,
fgao@ikuai8.com, ebiederm@xmission.com,
Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>,
Arnd Bergmann <arnd@arndb.de>,
Matt Fleming <matt@codeblueprint.co.uk>,
Mel Gorman <mgorman@techsingularity.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-doc@vger.kernel.org, linux-edac@vger.kernel.org,
kvm <kvm@vger.kernel.org>
Subject: [2/2] x86/idle: use dynamic halt poll
Date: Tue, 4 Jul 2017 16:50:54 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.20.1707041648540.9000@nanos> (raw)
On Tue, 4 Jul 2017, Radim Krčmář wrote:
> I think there is a nicer solution to avoid the expensive timer rewrite:
> Linux uses one-shot APIC timers and getting the timer interrupt is about
> as expensive as programming the timer, so the guest can keep the timer
> armed, but not re-arm it after the expiration if the CPU is idle.
So much for the theory. The NOHZ logic has to reprogram the timer when the
next expiry is farther away than the next tick. Otherwise you wake up on
every idle entry once for nothing, which defeats the whole purpose of NOHZ
to not do that.
Thanks,
tglx
next reply other threads:[~2017-07-04 14:50 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-04 14:50 Thomas Gleixner [this message]
-- strict thread matches above, loose matches on Subject: below --
2017-07-17 12:50 [2/2] x86/idle: use dynamic halt poll Yang Zhang
2017-07-17 9:54 Alexander Graf
2017-07-17 9:26 Yang Zhang
2017-07-14 9:37 Alexander Graf
2017-07-13 11:49 Yang Zhang
2017-07-04 22:28 Wanpeng Li
2017-07-04 14:13 Radim Krčmář
2017-07-04 2:19 Yang Zhang
2017-07-03 10:06 Thomas Gleixner
2017-07-03 9:28 Yang Zhang
2017-06-27 14:26 Paolo Bonzini
2017-06-27 14:22 Radim Krčmář
2017-06-27 13:56 Paolo Bonzini
2017-06-27 13:40 Radim Krčmář
2017-06-27 12:28 Paolo Bonzini
2017-06-27 12:23 Wanpeng Li
2017-06-27 12:07 Paolo Bonzini
2017-06-27 11:22 Yang Zhang
2017-06-23 4:04 Yang Zhang
2017-06-23 3:58 Yang Zhang
2017-06-22 22:46 kbuild test robot
2017-06-22 14:32 Thomas Gleixner
2017-06-22 11:51 Paolo Bonzini
2017-06-22 11:22 Yang Zhang
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