From: Marcelo Tosatti <mtosatti@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: kvm-devel <kvm@vger.kernel.org>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Bandan Das <bsd@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH] sched: introduce configurable delay before entering idle
Date: Tue, 7 May 2019 20:44:45 -0300 [thread overview]
Message-ID: <20190507234445.GA6185@amt.cnet> (raw)
In-Reply-To: <20190507221519.GE2677@hirez.programming.kicks-ass.net>
On Wed, May 08, 2019 at 12:15:19AM +0200, Peter Zijlstra wrote:
> On Tue, May 07, 2019 at 03:56:49PM -0300, Marcelo Tosatti wrote:
> >
> > Certain workloads perform poorly on KVM compared to baremetal
> > due to baremetal's ability to perform mwait on NEED_RESCHED
> > bit of task flags (therefore skipping the IPI).
> >
> > This patch introduces a configurable busy-wait delay before entering the
> > architecture delay routine, allowing wakeup IPIs to be skipped
> > (if the IPI happens in that window).
> >
> > The real-life workload which this patch improves performance
> > is SAP HANA (by 5-10%) (for which case setting idle_spin to 30
> > is sufficient).
> >
> > This patch improves the attached server.py and client.py example
> > as follows:
> >
> > Host: 31.814230202231556
> > Guest: 38.17718765199993 (83 %)
> > Guest, idle_spin=50us: 33.317709898000004 (95 %)
> > Guest, idle_spin=220us: 32.27826551499999 (98 %)
> >
> > Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
>
> Thanks for the CC..
>
> NAK, this is something that should live in a virt idle governor or
> something along those lines.
Ok, makes sense, will rework the patch!
next prev parent reply other threads:[~2019-05-07 23:45 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-07 18:56 [PATCH] sched: introduce configurable delay before entering idle Marcelo Tosatti
2019-05-07 22:15 ` Peter Zijlstra
2019-05-07 23:44 ` Marcelo Tosatti [this message]
2019-05-13 9:20 ` Wanpeng Li
2019-05-13 11:31 ` Konrad Rzeszutek Wilk
2019-05-13 11:51 ` Raslan, KarimAllah
2019-05-13 12:30 ` Boris Ostrovsky
2019-05-15 1:45 ` Wanpeng Li
2019-05-14 13:50 ` Marcelo Tosatti
2019-05-14 15:20 ` Konrad Rzeszutek Wilk
2019-05-14 17:42 ` Marcelo Tosatti
2019-05-15 1:42 ` Wanpeng Li
2019-05-15 20:26 ` Marcelo Tosatti
2019-05-15 18:42 ` Ankur Arora
2019-05-15 20:43 ` Marcelo Tosatti
2019-05-17 4:32 ` Ankur Arora
2019-05-17 17:49 ` Marcelo Tosatti
2019-05-16 1:07 ` Wanpeng Li
2019-05-17 2:06 ` Ankur Arora
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