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From: David Hildenbrand <david@redhat.com>
To: "Wang, Wei W" <wei.w.wang@intel.com>,
	'Nitesh Narayan Lal' <nitesh@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"lcapitulino@redhat.com" <lcapitulino@redhat.com>,
	"pagupta@redhat.com" <pagupta@redhat.com>,
	"yang.zhang.wz@gmail.com" <yang.zhang.wz@gmail.com>,
	"riel@surriel.com" <riel@surriel.com>,
	"dodgen@google.com" <dodgen@google.com>,
	"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>,
	"dhildenb@redhat.com" <dhildenb@redhat.com>,
	"aarcange@redhat.com" <aarcange@redhat.com>
Subject: Re: [RFC][Patch v8 0/7] KVM: Guest Free Page Hinting
Date: Thu, 14 Feb 2019 10:34:28 +0100	[thread overview]
Message-ID: <401883fd-bdad-6e34-cabe-c9b8fdadce92@redhat.com> (raw)
In-Reply-To: <286AC319A985734F985F78AFA26841F73DF6F1C3@shsmsx102.ccr.corp.intel.com>

On 14.02.19 10:12, Wang, Wei W wrote:
> On Thursday, February 14, 2019 1:22 AM, Nitesh Narayan Lal wrote:
>> In normal condition yes we would not like to report any memory when the
>> guest is already under memory pressure.
>>
>> I am not sure about the scenario where both guest and the host are under
>> memory pressure, who will be given priority? Is it something per-decided or
>> it depends on the use case?
>>
> 
> That's one of the reasons that I would vote for "host to ask for free pages".

As I already said, there are scenarios where this does not work reliably.

When we

1. Let the guest report free pages
2. Allow the hypervisor to enable/disable it

We have a mechanism that is superior to what you describe.

"host to ask for free pages" can be emulated using that.

> 
> Host can have a global view of all the guest's memory states, so better to have the
> memory overcommitment policy defined on the host.
> 
> For example, the host can know guest1 is under memory pressure (thus not asking him)
> and guest2 has a huge amount of free memory. When host lacks memory to run the 3rd
> guest, it can asks guest2 to offer some free memory. 
> 
> Best,
> Wei
> 


-- 

Thanks,

David / dhildenb

  parent reply	other threads:[~2019-02-14  9:34 UTC|newest]

Thread overview: 116+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-04 20:18 [RFC][Patch v8 0/7] KVM: Guest Free Page Hinting Nitesh Narayan Lal
2019-02-04 20:18 ` [RFC][Patch v8 1/7] KVM: Support for guest free page hinting Nitesh Narayan Lal
2019-02-05  4:14   ` Michael S. Tsirkin
2019-02-05 13:06     ` Nitesh Narayan Lal
2019-02-05 16:27       ` Michael S. Tsirkin
2019-02-05 16:34         ` Nitesh Narayan Lal
2019-02-04 20:18 ` [RFC][Patch v8 2/7] KVM: Enabling guest free page hinting via static key Nitesh Narayan Lal
2019-02-08 18:07   ` Alexander Duyck
2019-02-08 18:22     ` Nitesh Narayan Lal
2019-02-04 20:18 ` [RFC][Patch v8 3/7] KVM: Guest free page hinting functional skeleton Nitesh Narayan Lal
2019-02-04 20:18 ` [RFC][Patch v8 4/7] KVM: Disabling page poisoning to prevent corruption Nitesh Narayan Lal
2019-02-07 17:23   ` Alexander Duyck
2019-02-07 17:56     ` Nitesh Narayan Lal
2019-02-07 18:24       ` Alexander Duyck
2019-02-07 19:14         ` Michael S. Tsirkin
2019-02-07 21:08   ` Michael S. Tsirkin
2019-02-04 20:18 ` [RFC][Patch v8 5/7] virtio: Enables to add a single descriptor to the host Nitesh Narayan Lal
2019-02-05 20:49   ` Michael S. Tsirkin
2019-02-06 12:56     ` Nitesh Narayan Lal
2019-02-06 13:15       ` Luiz Capitulino
2019-02-06 13:24         ` Nitesh Narayan Lal
2019-02-06 13:29           ` Luiz Capitulino
2019-02-06 14:05             ` Nitesh Narayan Lal
2019-02-06 18:03       ` Michael S. Tsirkin
2019-02-06 18:19         ` Nitesh Narayan Lal
2019-02-04 20:18 ` [RFC][Patch v8 6/7] KVM: Enables the kernel to isolate and report free pages Nitesh Narayan Lal
2019-02-05 20:45   ` Michael S. Tsirkin
2019-02-05 21:54     ` Nitesh Narayan Lal
2019-02-05 21:55       ` Michael S. Tsirkin
2019-02-07 17:43         ` Alexander Duyck
2019-02-07 19:01           ` Michael S. Tsirkin
2019-02-07 20:50           ` Nitesh Narayan Lal
2019-02-08 17:58             ` Alexander Duyck
2019-02-08 20:41               ` Nitesh Narayan Lal
2019-02-08 21:38                 ` Michael S. Tsirkin
2019-02-08 22:05                   ` Alexander Duyck
2019-02-10  0:38                     ` Michael S. Tsirkin
2019-02-11  9:28                       ` David Hildenbrand
2019-02-12  5:16                         ` Michael S. Tsirkin
2019-02-12 17:10                       ` Nitesh Narayan Lal
2019-02-08 21:35               ` Michael S. Tsirkin
2019-02-04 20:18 ` [RFC][Patch v8 7/7] KVM: Adding tracepoints for guest page hinting Nitesh Narayan Lal
2019-02-04 20:20 ` [RFC][QEMU PATCH] KVM: Support for guest free " Nitesh Narayan Lal
2019-02-12  9:03 ` [RFC][Patch v8 0/7] KVM: Guest Free Page Hinting Wang, Wei W
2019-02-12  9:24   ` David Hildenbrand
2019-02-12 17:24     ` Nitesh Narayan Lal
2019-02-12 19:34       ` David Hildenbrand
2019-02-13  8:55     ` Wang, Wei W
2019-02-13  9:19       ` David Hildenbrand
2019-02-13 12:17         ` Nitesh Narayan Lal
2019-02-13 17:09           ` Michael S. Tsirkin
2019-02-13 17:22             ` Nitesh Narayan Lal
     [not found]               ` <286AC319A985734F985F78AFA26841F73DF6F1C3@shsmsx102.ccr.corp.intel.com>
2019-02-14  9:34                 ` David Hildenbrand [this message]
2019-02-13 17:16         ` Michael S. Tsirkin
2019-02-13 17:59           ` David Hildenbrand
2019-02-13 19:08             ` Michael S. Tsirkin
2019-02-14  9:08         ` Wang, Wei W
2019-02-14 10:00           ` David Hildenbrand
2019-02-14 10:44             ` David Hildenbrand
2019-02-15  9:15             ` Wang, Wei W
2019-02-15  9:33               ` David Hildenbrand
2019-02-13  9:00 ` Wang, Wei W
2019-02-13 12:06   ` Nitesh Narayan Lal
2019-02-14  8:48     ` Wang, Wei W
2019-02-14  9:42       ` David Hildenbrand
2019-02-15  9:05         ` Wang, Wei W
2019-02-15  9:41           ` David Hildenbrand
2019-02-18  2:36             ` Wei Wang
2019-02-18  2:39               ` Wei Wang
2019-02-15 12:40           ` Nitesh Narayan Lal
2019-02-14 13:00       ` Nitesh Narayan Lal
2019-02-16  9:40 ` David Hildenbrand
2019-02-18 15:50   ` Nitesh Narayan Lal
2019-02-18 16:02     ` David Hildenbrand
2019-02-18 16:49   ` Michael S. Tsirkin
2019-02-18 16:59     ` David Hildenbrand
2019-02-18 17:31       ` Alexander Duyck
2019-02-18 17:41         ` David Hildenbrand
2019-02-18 23:47           ` Alexander Duyck
2019-02-19  2:45             ` Michael S. Tsirkin
2019-02-19  2:46             ` Andrea Arcangeli
2019-02-19 12:52               ` Nitesh Narayan Lal
2019-02-19 16:23               ` Alexander Duyck
2019-02-19  8:06             ` David Hildenbrand
2019-02-19 14:40               ` Michael S. Tsirkin
2019-02-19 14:44                 ` David Hildenbrand
2019-02-19 14:45                   ` David Hildenbrand
2019-02-18 18:01         ` Michael S. Tsirkin
2019-02-18 17:54       ` Michael S. Tsirkin
2019-02-18 18:29         ` David Hildenbrand
2019-02-18 19:16           ` Michael S. Tsirkin
2019-02-18 19:35             ` David Hildenbrand
2019-02-18 19:47               ` Michael S. Tsirkin
2019-02-18 20:04                 ` David Hildenbrand
2019-02-18 20:31                   ` Michael S. Tsirkin
2019-02-18 20:40                     ` Nitesh Narayan Lal
2019-02-18 21:04                       ` David Hildenbrand
2019-02-19  0:01                         ` Alexander Duyck
2019-02-19  7:54                           ` David Hildenbrand
2019-02-19 18:06                             ` Alexander Duyck
2019-02-19 18:31                               ` David Hildenbrand
2019-02-19 21:57                                 ` Alexander Duyck
2019-02-19 22:17                                   ` Michael S. Tsirkin
2019-02-19 22:36                                   ` David Hildenbrand
2019-02-19 19:58                               ` Michael S. Tsirkin
2019-02-19 20:02                                 ` David Hildenbrand
2019-02-19 20:17                                   ` Michael S. Tsirkin
2019-02-19 20:21                                     ` David Hildenbrand
2019-02-19 20:35                                       ` Michael S. Tsirkin
2019-02-19 12:47                         ` Nitesh Narayan Lal
2019-02-19 13:03                           ` David Hildenbrand
2019-02-19 14:17                             ` Nitesh Narayan Lal
2019-02-19 14:21                               ` David Hildenbrand
2019-02-18 20:53                     ` David Hildenbrand
2019-02-23  0:02 ` Alexander Duyck
2019-02-25 13:01   ` Nitesh Narayan Lal

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