From: Paolo Bonzini <pbonzini@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: kvm-devel <kvm@vger.kernel.org>,
"Radim KrÄ?máÅ?" <rkrcmar@redhat.com>,
"Andrea Arcangeli" <aarcange@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Wanpeng Li" <kernellwp@gmail.com>,
"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
"Raslan KarimAllah" <karahmed@amazon.de>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Ankur Arora" <ankur.a.arora@oracle.com>,
"Christian Borntraeger" <borntraeger@de.ibm.com>,
"Linux PM" <linux-pm@vger.kernel.org>
Subject: Re: [patch 0/3] cpuidle-haltpoll driver (v2)
Date: Fri, 7 Jun 2019 20:22:35 +0200 [thread overview]
Message-ID: <9c3853cc-d920-03e8-245c-86c33b280c80@redhat.com> (raw)
In-Reply-To: <20190607171645.GA28275@amt.cnet>
On 07/06/19 19:16, Marcelo Tosatti wrote:
> There is no "target residency" concept in the virtualized use-case
> (which is what poll_state.c uses to calculate the poll time).
Actually there is: it is the cost of a vmexit, and it be calibrated with
a very short CPUID loop (e.g. run 100 CPUID instructions and take the
smallest TSC interval---it should take less than 50 microseconds, and
less than a millisecond even on nested virt).
I think it would make sense to improve poll_state.c to use an adaptive
algorithm similar to the one you implemented, which includes optionally
allowing to poll for an interval larger than the target residency.
Paolo
next prev parent reply other threads:[~2019-06-07 18:22 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190603225242.289109849@amt.cnet>
2019-06-07 9:49 ` [patch 0/3] cpuidle-haltpoll driver (v2) Rafael J. Wysocki
2019-06-07 17:16 ` Marcelo Tosatti
2019-06-07 18:22 ` Paolo Bonzini [this message]
2019-06-07 21:38 ` Marcelo Tosatti
2019-06-10 14:59 ` Marcelo Tosatti
2019-06-10 22:03 ` Rafael J. Wysocki
2019-06-11 14:26 ` Marcelo Tosatti
2019-06-11 21:24 ` Rafael J. Wysocki
2019-06-17 15:57 ` Peter Zijlstra
[not found] ` <20190603225254.212931277@amt.cnet>
2019-06-07 9:54 ` [patch 1/3] drivers/cpuidle: add cpuidle-haltpoll driver Rafael J. Wysocki
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