From: Vipin Sharma <vipinsh@google.com>
To: seanjc@google.com, pbonzini@redhat.com, bgardon@google.com,
dmatlack@google.com
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Vipin Sharma <vipinsh@google.com>
Subject: [Patch] KVM: x86/mmu: Make optimized __handle_changed_spte() for clear dirty log
Date: Wed, 25 Jan 2023 13:38:57 -0800 [thread overview]
Message-ID: <20230125213857.824959-1-vipinsh@google.com> (raw)
Use a tone down version of __handle_changed_spte() when clearing dirty
log. Remove checks which will not be needed when dirty logs are cleared.
This change shows ~13% improvement in clear dirty log calls in
dirty_log_perf_test
Before tone down version:
Clear dirty log over 3 iterations took 10.006764203s. (Avg 3.335588067s/iteration)
After tone down version:
Clear dirty log over 3 iterations took 8.686433554s. (Avg 2.895477851s/iteration)
Signed-off-by: Vipin Sharma <vipinsh@google.com>
---
arch/x86/kvm/mmu/tdp_mmu.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index bba33aea0fb0..ca21b33c4386 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -504,6 +504,19 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback);
}
+static void handle_changed_spte_clear_dirty_log(int as_id, gfn_t gfn,
+ u64 old_spte, u64 new_spte,
+ int level)
+{
+ if (old_spte == new_spte)
+ return;
+
+ trace_kvm_tdp_mmu_spte_changed(as_id, gfn, level, old_spte, new_spte);
+
+ if (is_dirty_spte(old_spte) && !is_dirty_spte(new_spte))
+ kvm_set_pfn_dirty(spte_to_pfn(old_spte));
+}
+
/**
* __handle_changed_spte - handle bookkeeping associated with an SPTE change
* @kvm: kvm instance
@@ -736,7 +749,12 @@ static u64 __tdp_mmu_set_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep,
old_spte = kvm_tdp_mmu_write_spte(sptep, old_spte, new_spte, level);
- __handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level, false);
+ if (record_dirty_log)
+ __handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte,
+ level, false);
+ else
+ handle_changed_spte_clear_dirty_log(as_id, gfn, old_spte,
+ new_spte, level);
if (record_acc_track)
handle_changed_spte_acc_track(old_spte, new_spte, level);
--
2.39.1.456.gfc5497dd1b-goog
next reply other threads:[~2023-01-25 21:39 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-25 21:38 Vipin Sharma [this message]
2023-01-25 22:00 ` [Patch] KVM: x86/mmu: Make optimized __handle_changed_spte() for clear dirty log David Matlack
2023-01-25 22:25 ` Ben Gardon
2023-01-26 0:40 ` Vipin Sharma
2023-01-26 1:49 ` Sean Christopherson
2023-01-28 17:20 ` Vipin Sharma
2023-01-30 18:09 ` Sean Christopherson
2023-01-30 20:17 ` Vipin Sharma
2023-01-30 22:49 ` Sean Christopherson
2023-01-30 22:12 ` David Matlack
2023-01-30 23:49 ` Sean Christopherson
2023-01-31 17:41 ` David Matlack
2023-01-31 18:01 ` Vipin Sharma
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