From: Oliver Upton <oliver.upton@linux.dev>
To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
Cc: "kvmarm@lists.linux.dev" <kvmarm@lists.linux.dev>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"maz@kernel.org" <maz@kernel.org>,
"will@kernel.org" <will@kernel.org>,
"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
"james.morse@arm.com" <james.morse@arm.com>,
"suzuki.poulose@arm.com" <suzuki.poulose@arm.com>,
yuzenghui <yuzenghui@huawei.com>,
zhukeqian <zhukeqian1@huawei.com>,
Jonathan Cameron <jonathan.cameron@huawei.com>,
Linuxarm <linuxarm@huawei.com>
Subject: Re: [RFC PATCH v2 0/8] KVM: arm64: Implement SW/HW combined dirty log
Date: Wed, 20 Sep 2023 21:12:29 +0000 [thread overview]
Message-ID: <ZQtgPSsOGgWE4MZ1@linux.dev> (raw)
In-Reply-To: <853b333084c4462a870bb2a37ec65935@huawei.com>
On Mon, Sep 18, 2023 at 09:55:22AM +0000, Shameerali Kolothum Thodi wrote:
[...]
> > Sorry, this was rather nonspecific. I was describing the pre-copy
> > strategies we're using at Google (out of tree). We're carrying patches
> > to use EPT D-bit for exitless dirty tracking.
>
> Just curious, how does it handle the overheads associated with scanning for
> dirty pages and the convergence w.r.t high rate of dirtying in exitless mode?
A pool of kthreads, which really isn't a good solution at all. The
'better' way to do it would be to add some back pressure to the guest
such that your pre-copy transfer can converge with the guest and use the
freed up CPU time to manage the dirty state.
But hopefully we can make that a userspace issue.
--
Thanks,
Oliver
WARNING: multiple messages have this Message-ID (diff)
From: Oliver Upton <oliver.upton@linux.dev>
To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
Cc: "kvmarm@lists.linux.dev" <kvmarm@lists.linux.dev>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"maz@kernel.org" <maz@kernel.org>,
"will@kernel.org" <will@kernel.org>,
"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
"james.morse@arm.com" <james.morse@arm.com>,
"suzuki.poulose@arm.com" <suzuki.poulose@arm.com>,
yuzenghui <yuzenghui@huawei.com>,
zhukeqian <zhukeqian1@huawei.com>,
Jonathan Cameron <jonathan.cameron@huawei.com>,
Linuxarm <linuxarm@huawei.com>
Subject: Re: [RFC PATCH v2 0/8] KVM: arm64: Implement SW/HW combined dirty log
Date: Wed, 20 Sep 2023 21:12:29 +0000 [thread overview]
Message-ID: <ZQtgPSsOGgWE4MZ1@linux.dev> (raw)
In-Reply-To: <853b333084c4462a870bb2a37ec65935@huawei.com>
On Mon, Sep 18, 2023 at 09:55:22AM +0000, Shameerali Kolothum Thodi wrote:
[...]
> > Sorry, this was rather nonspecific. I was describing the pre-copy
> > strategies we're using at Google (out of tree). We're carrying patches
> > to use EPT D-bit for exitless dirty tracking.
>
> Just curious, how does it handle the overheads associated with scanning for
> dirty pages and the convergence w.r.t high rate of dirtying in exitless mode?
A pool of kthreads, which really isn't a good solution at all. The
'better' way to do it would be to add some back pressure to the guest
such that your pre-copy transfer can converge with the guest and use the
freed up CPU time to manage the dirty state.
But hopefully we can make that a userspace issue.
--
Thanks,
Oliver
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-09-20 21:12 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-25 9:35 [RFC PATCH v2 0/8] KVM: arm64: Implement SW/HW combined dirty log Shameer Kolothum
2023-08-25 9:35 ` Shameer Kolothum
2023-08-25 9:35 ` [RFC PATCH v2 1/8] arm64: cpufeature: Add API to report system support of HWDBM Shameer Kolothum
2023-08-25 9:35 ` Shameer Kolothum
2023-08-25 9:35 ` [RFC PATCH v2 2/8] KVM: arm64: Add KVM_PGTABLE_WALK_HW_DBM for HW DBM support Shameer Kolothum
2023-08-25 9:35 ` Shameer Kolothum
2023-09-15 22:05 ` Oliver Upton
2023-09-15 22:05 ` Oliver Upton
2023-09-18 9:52 ` Shameerali Kolothum Thodi
2023-09-18 9:52 ` Shameerali Kolothum Thodi
2023-08-25 9:35 ` [RFC PATCH v2 3/8] KVM: arm64: Add some HW_DBM related pgtable interfaces Shameer Kolothum
2023-08-25 9:35 ` Shameer Kolothum
2023-09-15 22:22 ` Oliver Upton
2023-09-15 22:22 ` Oliver Upton
2023-09-18 9:53 ` Shameerali Kolothum Thodi
2023-09-18 9:53 ` Shameerali Kolothum Thodi
2023-09-22 15:24 ` Catalin Marinas
2023-09-22 15:24 ` Catalin Marinas
2023-09-22 17:49 ` Oliver Upton
2023-09-22 17:49 ` Oliver Upton
2023-09-25 8:04 ` Shameerali Kolothum Thodi
2023-09-25 8:04 ` Shameerali Kolothum Thodi
2023-09-26 15:20 ` Catalin Marinas
2023-09-26 15:20 ` Catalin Marinas
2023-09-26 15:52 ` Shameerali Kolothum Thodi
2023-09-26 15:52 ` Shameerali Kolothum Thodi
2023-09-26 16:37 ` Catalin Marinas
2023-09-26 16:37 ` Catalin Marinas
2023-08-25 9:35 ` [RFC PATCH v2 4/8] KVM: arm64: Set DBM for previously writeable pages Shameer Kolothum
2023-08-25 9:35 ` Shameer Kolothum
2023-09-15 22:54 ` Oliver Upton
2023-09-15 22:54 ` Oliver Upton
2023-09-18 9:54 ` Shameerali Kolothum Thodi
2023-09-18 9:54 ` Shameerali Kolothum Thodi
2023-09-22 15:40 ` Catalin Marinas
2023-09-22 15:40 ` Catalin Marinas
2023-09-25 8:04 ` Shameerali Kolothum Thodi
2023-09-25 8:04 ` Shameerali Kolothum Thodi
2023-08-25 9:35 ` [RFC PATCH v2 5/8] KVM: arm64: Add some HW_DBM related mmu interfaces Shameer Kolothum
2023-08-25 9:35 ` Shameer Kolothum
2023-08-25 9:35 ` [RFC PATCH v2 6/8] KVM: arm64: Only write protect selected PTE Shameer Kolothum
2023-08-25 9:35 ` Shameer Kolothum
2023-09-22 16:00 ` Catalin Marinas
2023-09-22 16:00 ` Catalin Marinas
2023-09-22 16:59 ` Oliver Upton
2023-09-22 16:59 ` Oliver Upton
2023-09-26 15:58 ` Catalin Marinas
2023-09-26 15:58 ` Catalin Marinas
2023-09-26 16:10 ` Catalin Marinas
2023-09-26 16:10 ` Catalin Marinas
2023-08-25 9:35 ` [RFC PATCH v2 7/8] KVM: arm64: Add KVM_CAP_ARM_HW_DBM Shameer Kolothum
2023-08-25 9:35 ` Shameer Kolothum
2023-08-25 9:35 ` [RFC PATCH v2 8/8] KVM: arm64: Start up SW/HW combined dirty log Shameer Kolothum
2023-08-25 9:35 ` Shameer Kolothum
2023-09-13 17:30 ` [RFC PATCH v2 0/8] KVM: arm64: Implement " Oliver Upton
2023-09-13 17:30 ` Oliver Upton
2023-09-14 9:47 ` Shameerali Kolothum Thodi
2023-09-14 9:47 ` Shameerali Kolothum Thodi
2023-09-15 0:36 ` Oliver Upton
2023-09-15 0:36 ` Oliver Upton
2023-09-18 9:55 ` Shameerali Kolothum Thodi
2023-09-18 9:55 ` Shameerali Kolothum Thodi
2023-09-20 21:12 ` Oliver Upton [this message]
2023-09-20 21:12 ` Oliver Upton
2023-10-12 7:51 ` Shameerali Kolothum Thodi
2023-10-12 7:51 ` Shameerali Kolothum Thodi
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