From: Sean Christopherson <seanjc@google.com>
To: Zdenek Kaspar <zkaspar82@gmail.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: Bad performance since 5.9-rc1
Date: Tue, 22 Dec 2020 09:07:39 -0800 [thread overview]
Message-ID: <X+In2zIA40Ku19cM@google.com> (raw)
In-Reply-To: <20201221221339.030684c4.zkaspar82@gmail.com>
On Mon, Dec 21, 2020, Zdenek Kaspar wrote:
> [ 179.364305] WARNING: CPU: 0 PID: 369 at kvm_mmu_zap_oldest_mmu_pages+0xd1/0xe0 [kvm]
> [ 179.365415] Call Trace:
> [ 179.365443] paging64_page_fault+0x244/0x8e0 [kvm]
This means the shadow page zapping is occuring because KVM is hitting the max
number of allowed MMU shadow pages. Can you provide your QEMU command line? I
can reproduce the performance degredation, but only by deliberately overriding
the max number of MMU pages via `-machine kvm-shadow-mem` to be an absurdly low
value.
> [ 179.365596] kvm_mmu_page_fault+0x376/0x550 [kvm]
> [ 179.365725] kvm_arch_vcpu_ioctl_run+0xbaf/0x18f0 [kvm]
> [ 179.365772] kvm_vcpu_ioctl+0x203/0x520 [kvm]
> [ 179.365938] __x64_sys_ioctl+0x338/0x720
> [ 179.365992] do_syscall_64+0x33/0x40
> [ 179.366013] entry_SYSCALL_64_after_hwframe+0x44/0xa9
next prev parent reply other threads:[~2020-12-22 17:08 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 3:05 Bad performance since 5.9-rc1 Zdenek Kaspar
2020-12-01 6:35 ` Zdenek Kaspar
2020-12-18 19:33 ` Zdenek Kaspar
2020-12-21 19:41 ` Sean Christopherson
2020-12-21 21:13 ` Zdenek Kaspar
2020-12-22 17:07 ` Sean Christopherson [this message]
2020-12-22 21:26 ` Zdenek Kaspar
2021-01-12 11:18 ` Zdenek Kaspar
2021-01-13 20:17 ` Sean Christopherson
2021-01-13 22:17 ` Zdenek Kaspar
2020-12-02 0:31 ` Sean Christopherson
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