From: Shivam Kumar <shivam.kumar1@nutanix.com>
To: Sean Christopherson <seanjc@google.com>
Cc: pbonzini@redhat.com, kvm@vger.kernel.org,
Anurag Madnawat <anurag.madnawat@nutanix.com>,
Shaju Abraham <shaju.abraham@nutanix.com>,
Manish Mishra <manish.mishra@nutanix.com>
Subject: Re: [PATCH 4/6] Increment dirty counter for vmexit due to page write fault.
Date: Sat, 20 Nov 2021 01:24:14 +0530 [thread overview]
Message-ID: <7722707c-cae1-4198-9189-923e96b2bdab@nutanix.com> (raw)
In-Reply-To: <YZaR4U5r3j7zWBIF@google.com>
On 18/11/21 11:18 pm, Sean Christopherson wrote:
> On Sun, Nov 14, 2021, Shivam Kumar wrote:
>> For a page write fault or "page dirty", the dirty counter of the
>> corresponding vCPU is incremented.
>>
>> Co-developed-by: Anurag Madnawat <anurag.madnawat@nutanix.com>
>> Signed-off-by: Anurag Madnawat <anurag.madnawat@nutanix.com>
>> Signed-off-by: Shivam Kumar <shivam.kumar1@nutanix.com>
>> Signed-off-by: Shaju Abraham <shaju.abraham@nutanix.com>
>> Signed-off-by: Manish Mishra <manish.mishra@nutanix.com>
>> ---
>> virt/kvm/kvm_main.c | 9 ++++++++-
>> 1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>> index 1564d3a3f608..55bf92cf9f4f 100644
>> --- a/virt/kvm/kvm_main.c
>> +++ b/virt/kvm/kvm_main.c
>> @@ -3091,8 +3091,15 @@ void mark_page_dirty_in_slot(struct kvm *kvm,
>> if (kvm->dirty_ring_size)
>> kvm_dirty_ring_push(kvm_dirty_ring_get(kvm),
>> slot, rel_gfn);
>> - else
>> + else {
>> + struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
>> +
>> + if (vcpu && vcpu->kvm->dirty_quota_migration_enabled &&
>> + vcpu->vCPUdqctx)
>> + vcpu->vCPUdqctx->dirty_counter++;
> Checking dirty_quota_migration_enabled can race, and it'd be far faster to
> unconditionally update a counter, e.g. a per-vCPU stat.
Yes, unconditional update seems fine as it is not required to reset the
dirty counter every time a new migration starts (as per our discussion
on PATCH 0 in this patchset). Thanks.
>
>> +
>> set_bit_le(rel_gfn, memslot->dirty_bitmap);
>> + }
>> }
>> }
>> EXPORT_SYMBOL_GPL(mark_page_dirty_in_slot);
>> --
>> 2.22.3
>>
next prev parent reply other threads:[~2021-11-19 19:54 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-14 14:57 [PATCH 0/6] KVM: Dirty Quota-Based VM Live Migration Auto-Converge Shivam Kumar
2021-11-14 14:57 ` [PATCH 1/6] Define data structures for dirty quota migration Shivam Kumar
2021-11-14 14:57 ` [PATCH 2/6] Init dirty quota flag and allocate memory for vCPUdqctx Shivam Kumar
2021-11-14 14:57 ` [PATCH 3/6] Add KVM_CAP_DIRTY_QUOTA_MIGRATION and handle vCPU page faults Shivam Kumar
2021-11-18 17:57 ` Sean Christopherson
2021-11-19 20:03 ` Shivam Kumar
[not found] ` <02b8fa86-a86b-969e-2137-1953639cb6d2@nutanix.com>
[not found] ` <YZgD0D4536s2DMem@google.com>
2021-11-19 20:21 ` Shivam Kumar
2021-11-25 8:43 ` Shivam Kumar
2021-12-01 17:22 ` Sean Christopherson
2021-11-14 14:57 ` [PATCH 4/6] Increment dirty counter for vmexit due to page write fault Shivam Kumar
2021-11-18 17:48 ` Sean Christopherson
2021-11-19 19:54 ` Shivam Kumar [this message]
2021-11-14 14:57 ` [PATCH 5/6] Exit to userspace when dirty quota is full Shivam Kumar
2021-11-14 14:57 ` [PATCH 6/6] Free vCPUdqctx memory on vCPU destroy Shivam Kumar
2021-11-18 17:46 ` [PATCH 0/6] KVM: Dirty Quota-Based VM Live Migration Auto-Converge Sean Christopherson
-- strict thread matches above, loose matches on Subject: below --
2021-10-26 16:35 Shivam Kumar
2021-10-26 16:35 ` [PATCH 4/6] Increment dirty counter for vmexit due to page write fault Shivam Kumar
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