* [PATCH v2] KVM: x86/mmu: Speed up slot_rmap_walk_next for sparsely populated rmaps
@ 2022-05-02 22:03 Vipin Sharma
2022-05-03 9:32 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: Vipin Sharma @ 2022-05-02 22:03 UTC (permalink / raw)
To: pbonzini
Cc: seanjc, vkuznets, wanpengli, jmattson, joro, dmatlack, kvm,
linux-kernel, Vipin Sharma
Avoid calling handlers on empty rmap entries and skip to the next non
empty rmap entry.
Empty rmap entries are noop in handlers.
Signed-off-by: Vipin Sharma <vipinsh@google.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
---
v2:
- Removed noinline from slot_rmap_walk_next signature
v1:
- https://lore.kernel.org/lkml/20220325233125.413634-1-vipinsh@google.com
arch/x86/kvm/mmu/mmu.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 77785587332e..4e8d546431eb 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1501,9 +1501,11 @@ static bool slot_rmap_walk_okay(struct slot_rmap_walk_iterator *iterator)
static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator)
{
- if (++iterator->rmap <= iterator->end_rmap) {
+ while (++iterator->rmap <= iterator->end_rmap) {
iterator->gfn += (1UL << KVM_HPAGE_GFN_SHIFT(iterator->level));
- return;
+
+ if (iterator->rmap->val)
+ return;
}
if (++iterator->level > iterator->end_level) {
base-commit: 71d7c575a673d42ad7175ad5fc27c85c80330311
--
2.36.0.464.gb9c8b46e94-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] KVM: x86/mmu: Speed up slot_rmap_walk_next for sparsely populated rmaps
2022-05-02 22:03 [PATCH v2] KVM: x86/mmu: Speed up slot_rmap_walk_next for sparsely populated rmaps Vipin Sharma
@ 2022-05-03 9:32 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2022-05-03 9:32 UTC (permalink / raw)
To: Vipin Sharma
Cc: seanjc, vkuznets, wanpengli, jmattson, joro, dmatlack, kvm, linux-kernel
On 5/3/22 00:03, Vipin Sharma wrote:
> Avoid calling handlers on empty rmap entries and skip to the next non
> empty rmap entry.
>
> Empty rmap entries are noop in handlers.
>
> Signed-off-by: Vipin Sharma <vipinsh@google.com>
> Suggested-by: Sean Christopherson <seanjc@google.com>
> ---
>
> v2:
> - Removed noinline from slot_rmap_walk_next signature
>
> v1:
> - https://lore.kernel.org/lkml/20220325233125.413634-1-vipinsh@google.com
>
> arch/x86/kvm/mmu/mmu.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 77785587332e..4e8d546431eb 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -1501,9 +1501,11 @@ static bool slot_rmap_walk_okay(struct slot_rmap_walk_iterator *iterator)
>
> static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator)
> {
> - if (++iterator->rmap <= iterator->end_rmap) {
> + while (++iterator->rmap <= iterator->end_rmap) {
> iterator->gfn += (1UL << KVM_HPAGE_GFN_SHIFT(iterator->level));
> - return;
> +
> + if (iterator->rmap->val)
> + return;
> }
>
> if (++iterator->level > iterator->end_level) {
>
> base-commit: 71d7c575a673d42ad7175ad5fc27c85c80330311
Queued, thanks.
Paolo
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