From: Avi Kivity <avi@redhat.com>
To: Raghavendra K T <raghukt@linux.vnet.ibm.com>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
KVM <kvm@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
Dave Jiang <dave.jiang@intel.com>,
x86@kernel.org, Ingo Molnar <mingo@redhat.com>,
Rik van Riel <riel@redhat.com>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Xen <xen-devel@lists.xensource.com>,
Sedat Dilek <sedat.dilek@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Virtualization <virtualization@lists.linux-foundation.org>,
Yinghai Lu <yinghai@kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Greg Kroah-Hartman <gregkh@suse.de>,
LKML <linux-kernel@vger.kernel.org>,
Suzuki Poulose <suzuki@linux.vnet.ibm.com>
Subject: Re: [PATCH RFC V2 3/5] kvm hypervisor : Add two hypercalls to support pv-ticketlock
Date: Thu, 27 Oct 2011 12:17:15 +0200 [thread overview]
Message-ID: <4EA92FAB.1050607@redhat.com> (raw)
In-Reply-To: <4EA85A9D.5060203@linux.vnet.ibm.com>
On 10/26/2011 09:08 PM, Raghavendra K T wrote:
> On 10/26/2011 04:04 PM, Avi Kivity wrote:
>> On 10/25/2011 08:24 PM, Raghavendra K T wrote:
> CCing Ryan also
>>>
>>> So then do also you foresee the need for directed yield at some point,
>>> to address LHP? provided we have good improvements to prove.
>>
>> Doesn't this patchset completely eliminate lock holder preemption?
>>
> Basically I was curious whether we can do more better with your
> directed yield discussions in https://lkml.org/lkml/2010/8/2/106 .
>
> I felt we can get little more improvement with doing directed yield to
> lock-holder in case of LHP than sleeping. But I may be wrong.
>
> So wanted to get the feedback, on whether I am thinking in right
> direction.
i guess donating some time to the lock holder could help, but not by
much. The problem with non-pv spinlocks is that you can't just sleep,
since no one will wake you up, so you have to actively boost the lock
holder.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@redhat.com>
To: Raghavendra K T <raghukt@linux.vnet.ibm.com>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
Greg Kroah-Hartman <gregkh@suse.de>,
"H. Peter Anvin" <hpa@zytor.com>, Gleb Natapov <gleb@redhat.com>,
Virtualization <virtualization@lists.linux-foundation.org>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
x86@kernel.org, KVM <kvm@vger.kernel.org>,
Dave Jiang <dave.jiang@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Xen <xen-devel@lists.xensource.com>,
Sedat Dilek <sedat.dilek@gmail.com>,
Yinghai Lu <yinghai@kernel.org>,
Marcelo Tosatti <mtosatti@redhat.com>,
Ingo Molnar <mingo@redhat.com>, Rik van Riel <riel@redhat.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
LKML <linux-kernel@vger.kernel.org>,
Suzuki Poulose <suzuki@linux.vnet.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
Ryan Harper <ryanh@us.ibm.com>
Subject: Re: [PATCH RFC V2 3/5] kvm hypervisor : Add two hypercalls to support pv-ticketlock
Date: Thu, 27 Oct 2011 12:17:15 +0200 [thread overview]
Message-ID: <4EA92FAB.1050607@redhat.com> (raw)
In-Reply-To: <4EA85A9D.5060203@linux.vnet.ibm.com>
On 10/26/2011 09:08 PM, Raghavendra K T wrote:
> On 10/26/2011 04:04 PM, Avi Kivity wrote:
>> On 10/25/2011 08:24 PM, Raghavendra K T wrote:
> CCing Ryan also
>>>
>>> So then do also you foresee the need for directed yield at some point,
>>> to address LHP? provided we have good improvements to prove.
>>
>> Doesn't this patchset completely eliminate lock holder preemption?
>>
> Basically I was curious whether we can do more better with your
> directed yield discussions in https://lkml.org/lkml/2010/8/2/106 .
>
> I felt we can get little more improvement with doing directed yield to
> lock-holder in case of LHP than sleeping. But I may be wrong.
>
> So wanted to get the feedback, on whether I am thinking in right
> direction.
i guess donating some time to the lock holder could help, but not by
much. The problem with non-pv spinlocks is that you can't just sleep,
since no one will wake you up, so you have to actively boost the lock
holder.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2011-10-27 10:17 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-23 19:03 [PATCH RFC V2 0/5] kvm : Paravirt-spinlock support for KVM guests Raghavendra K T
2011-10-23 19:03 ` Raghavendra K T
2011-10-23 19:04 ` [PATCH RFC V2 1/5] debugfs: Add support to print u32 array in debugfs Raghavendra K T
2011-10-23 22:20 ` Greg KH
2011-10-24 9:30 ` Raghavendra K T
2011-10-23 19:04 ` Raghavendra K T
2011-10-23 19:04 ` Raghavendra K T
2011-10-23 19:04 ` [PATCH RFC V2 2/5] debugfs: Renaming of xen functions and change unsigned to u32 Raghavendra K T
2011-10-23 19:04 ` Raghavendra K T
2011-10-23 22:19 ` Greg KH
2011-10-24 9:28 ` Raghavendra K T
2011-10-24 9:38 ` Greg KH
2011-10-23 19:04 ` Raghavendra K T
2011-10-23 19:05 ` [PATCH RFC V2 3/5] kvm hypervisor : Add two hypercalls to support pv-ticketlock Raghavendra K T
2011-10-23 19:05 ` Raghavendra K T
2011-10-24 10:01 ` Sasha Levin
2011-10-24 10:01 ` Sasha Levin
2011-10-24 11:00 ` Raghavendra K T
2011-10-24 11:00 ` Raghavendra K T
2011-10-24 11:00 ` Raghavendra K T
2011-10-24 10:14 ` Avi Kivity
2011-10-24 11:20 ` Raghavendra K T
2011-10-24 12:27 ` Srivatsa Vaddagiri
2011-10-24 13:09 ` Avi Kivity
2011-10-24 13:50 ` Srivatsa Vaddagiri
2011-10-25 18:24 ` Raghavendra K T
2011-10-26 10:34 ` Avi Kivity
2011-10-26 19:08 ` Raghavendra K T
2011-10-26 19:08 ` Raghavendra K T
2011-10-26 19:08 ` Raghavendra K T
2011-10-27 10:17 ` Avi Kivity [this message]
2011-10-27 10:17 ` Avi Kivity
2011-10-26 20:09 ` Jeremy Fitzhardinge
2011-10-26 20:09 ` Jeremy Fitzhardinge
2011-10-26 20:09 ` Jeremy Fitzhardinge
2011-10-23 19:05 ` Raghavendra K T
2011-10-23 19:07 ` [PATCH RFC V2 4/5] kvm guest : Added configuration support to enable debug information for KVM Guests Raghavendra K T
2011-10-23 19:07 ` Raghavendra K T
2011-10-23 19:07 ` Raghavendra K T
2011-10-24 10:01 ` Sasha Levin
2011-10-24 10:01 ` Sasha Levin
2011-10-24 18:45 ` Raghavendra K T
2011-10-24 18:45 ` Raghavendra K T
2011-10-24 18:45 ` Raghavendra K T
2011-10-24 10:15 ` Avi Kivity
2011-10-25 18:11 ` Raghavendra K T
2011-10-25 18:30 ` Jeremy Fitzhardinge
2011-10-23 19:07 ` [PATCH RFC V2 5/5] kvm guest : pv-ticketlocks support for linux guests running on KVM hypervisor Raghavendra K T
2011-10-23 19:07 ` Raghavendra K T
2011-10-24 10:01 ` Sasha Levin
2011-10-24 9:33 ` Raghavendra K T
2011-10-24 9:33 ` Raghavendra K T
2011-10-24 9:33 ` Raghavendra K T
2011-10-25 18:34 ` Jeremy Fitzhardinge
2011-10-26 19:23 ` Raghavendra K T
2011-10-26 19:46 ` Jeremy Fitzhardinge
2011-10-26 19:55 ` Raghavendra K T
2011-10-25 18:35 ` Jeremy Fitzhardinge
2011-10-26 19:25 ` Raghavendra K T
2011-10-23 19:07 ` Raghavendra K T
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