linux-kernel - Re: [RFC][Patch v8 0/7] KVM: Guest Free Page Hinting

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Message-ID: <5d59937c-ba70-701d-7d15-815b211fce05@redhat.com>
Date:   Thu, 14 Feb 2019 08:00:57 -0500
From:   Nitesh Narayan Lal <nitesh@...hat.com>
To:     "Wang, Wei W" <wei.w.wang@...el.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "lcapitulino@...hat.com" <lcapitulino@...hat.com>,
        "pagupta@...hat.com" <pagupta@...hat.com>,
        "yang.zhang.wz@...il.com" <yang.zhang.wz@...il.com>,
        "riel@...riel.com" <riel@...riel.com>,
        "david@...hat.com" <david@...hat.com>,
        "mst@...hat.com" <mst@...hat.com>,
        "dodgen@...gle.com" <dodgen@...gle.com>,
        "konrad.wilk@...cle.com" <konrad.wilk@...cle.com>,
        "dhildenb@...hat.com" <dhildenb@...hat.com>,
        "aarcange@...hat.com" <aarcange@...hat.com>
Subject: Re: [RFC][Patch v8 0/7] KVM: Guest Free Page Hinting


On 2/14/19 3:48 AM, Wang, Wei W wrote:
> On Wednesday, February 13, 2019 8:07 PM, Nitesh Narayan Lal wrote:
>> Once the host free the pages. All the isolated pages are returned back 
>> to the buddy. (This is implemented in hyperlist_ready())
> This actually has the same issue: the isolated pages have to wait to return to the buddy
> after the host has done with madvise(DONTNEED). Otherwise, a page could be used by
> a guest thread and the next moment the host takes it to other host threads.
I don't think that this will be a blocking case. Let's say there are
pages from the normal zone which are isolated and are currently freed by
the host at this point even if the normal zone runs out of free pages,
any allocation request could be served from another zone which will have
free pages.
>
> Best,
> Wei
-- 
Regards
Nitesh



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