From: James Houghton <jthoughton@google.com>
To: David Matlack <dmatlack@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Paolo Bonzini <pbonzini@redhat.com>, Yu Zhao <yuzhao@google.com>,
Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
Sean Christopherson <seanjc@google.com>,
Jonathan Corbet <corbet@lwn.net>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Shaoqin Huang <shahuang@redhat.com>,
Gavin Shan <gshan@redhat.com>,
Ricardo Koller <ricarkol@google.com>,
Raghavendra Rao Ananta <rananta@google.com>,
Ryan Roberts <ryan.roberts@arm.com>,
David Rientjes <rientjes@google.com>,
Axel Rasmussen <axelrasmussen@google.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
kvm@vger.kernel.org, linux-mm@kvack.org,
linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH v3 0/7] mm/kvm: Improve parallelism for access bit harvesting
Date: Fri, 19 Apr 2024 13:57:03 -0700 [thread overview]
Message-ID: <CADrL8HW+4Yq-wBr1+DzJvSwRRL_hqt5RaCCLgOQndPGUqoX+Rg@mail.gmail.com> (raw)
In-Reply-To: <ZhmAR1akBHjvZ9_4@google.com>
On Fri, Apr 12, 2024 at 11:41 AM David Matlack <dmatlack@google.com> wrote:
>
> On 2024-04-01 11:29 PM, James Houghton wrote:
> > This patchset adds a fast path in KVM to test and clear access bits on
> > sptes without taking the mmu_lock. It also adds support for using a
> > bitmap to (1) test the access bits for many sptes in a single call to
> > mmu_notifier_test_young, and to (2) clear the access bits for many ptes
> > in a single call to mmu_notifier_clear_young.
>
> How much improvement would we get if we _just_ made test/clear_young
> lockless on x86 and hold the read-lock on arm64? And then how much
> benefit does the bitmap look-around add on top of that?
I don't have these results right now. For the next version I will (1)
separate the series into the locking change and the bitmap change, and
I will (2) have performance data for each change separately. It is
conceivable that the bitmap change should just be considered as a
completely separate patchset.
next prev parent reply other threads:[~2024-04-19 20:57 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-01 23:29 James Houghton
2024-04-01 23:29 ` [PATCH v3 1/7] mm: Add a bitmap into mmu_notifier_{clear,test}_young James Houghton
2024-04-04 18:52 ` David Hildenbrand
2024-04-09 18:31 ` James Houghton
2024-04-09 19:35 ` David Hildenbrand
2024-04-11 0:35 ` James Houghton
2024-04-12 18:45 ` David Matlack
2024-04-19 20:34 ` James Houghton
2024-04-01 23:29 ` [PATCH v3 2/7] KVM: Move MMU notifier function declarations James Houghton
2024-04-01 23:29 ` [PATCH v3 3/7] KVM: Add basic bitmap support into kvm_mmu_notifier_test/clear_young James Houghton
2024-04-12 20:28 ` David Matlack
2024-04-19 20:41 ` James Houghton
2024-04-01 23:29 ` [PATCH v3 4/7] KVM: x86: Move tdp_mmu_enabled and shadow_accessed_mask James Houghton
2024-04-01 23:29 ` [PATCH v3 5/7] KVM: x86: Participate in bitmap-based PTE aging James Houghton
2024-04-11 17:08 ` David Matlack
2024-04-11 17:28 ` David Matlack
2024-04-11 18:00 ` David Matlack
2024-04-11 18:07 ` David Matlack
2024-04-19 20:47 ` James Houghton
2024-04-19 21:06 ` David Matlack
2024-04-19 21:48 ` James Houghton
2024-04-21 0:19 ` Yu Zhao
2024-04-12 20:44 ` David Matlack
2024-04-19 20:54 ` James Houghton
2024-04-01 23:29 ` [PATCH v3 6/7] KVM: arm64: " James Houghton
2024-04-02 4:06 ` Yu Zhao
2024-04-02 7:00 ` Oliver Upton
2024-04-02 7:33 ` Marc Zyngier
2024-04-01 23:29 ` [PATCH v3 7/7] mm: multi-gen LRU: use mmu_notifier_test_clear_young() James Houghton
2024-04-12 18:41 ` [PATCH v3 0/7] mm/kvm: Improve parallelism for access bit harvesting David Matlack
2024-04-19 20:57 ` James Houghton [this message]
2024-04-19 22:23 ` Oliver Upton
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