On Fri, Aug 10, 2012 at 05:16:12PM +0900, Takuya Yoshikawa wrote:
> The following commit changed mmu_shrink() so that it would skip VMs
> whose n_used_mmu_pages was not zero and try to free pages from others:
>
> commit 1952639665e92481c34c34c3e2a71bf3e66ba362
> KVM: MMU: do not iterate over all VMs in mmu_shrink()
>
> This patch fixes the function so that it can free mmu pages as before.
> Note that "if (!nr_to_scan--)" check is removed since we do not try to
> free mmu pages from more than one VM.
>
> Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@xxxxxxxxxxxxx>
> Cc: Gleb Natapov <gleb@xxxxxxxxxx>
> ---
> This patch just recovers the original behaviour and is not related
> to how to improve mmu_shrink() further; so please apply.
Before 1952639665e92481c34 the code was maxed at nr_to_scan loops. So
removing if (!nr_to_scan--) patch does change behaviour.
Am i missing something here?
> arch/x86/kvm/mmu.c | 5 +----
> 1 files changed, 1 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 9651c2c..4aeec72 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -4154,11 +4154,8 @@ static int mmu_shrink(struct shrinker *shrink, struct shrink_control *sc)
> * want to shrink a VM that only started to populate its MMU
> * anyway.
> */
> - if (kvm->arch.n_used_mmu_pages > 0) {
> - if (!nr_to_scan--)
> - break;
> + if (!kvm->arch.n_used_mmu_pages)
> continue;
> - }
>
> idx = srcu_read_lock(&kvm->srcu);
> spin_lock(&kvm->mmu_lock);
> --
> 1.7.5.4
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