From: Lance Yang <lance.yang@linux.dev>
To: Dave Hansen <dave.hansen@intel.com>,
"David Hildenbrand (Arm)" <david@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Cc: Liam.Howlett@oracle.com, akpm@linux-foundation.org,
aneesh.kumar@kernel.org, arnd@arndb.de, baohua@kernel.org,
baolin.wang@linux.alibaba.com, boris.ostrovsky@oracle.com,
bp@alien8.de, dave.hansen@linux.intel.com, dev.jain@arm.com,
hpa@zytor.com, hughd@google.com, ioworker0@gmail.com,
jannh@google.com, jgross@suse.com, kvm@vger.kernel.org,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, lorenzo.stoakes@oracle.com, mingo@redhat.com,
npache@redhat.com, npiggin@gmail.com, pbonzini@redhat.com,
riel@surriel.com, ryan.roberts@arm.com, seanjc@google.com,
shy828301@gmail.com, tglx@linutronix.de,
virtualization@lists.linux.dev, will@kernel.org, x86@kernel.org,
ypodemsk@redhat.com, ziy@nvidia.com
Subject: Re: [PATCH v4 0/3] targeted TLB sync IPIs for lockless page table
Date: Thu, 5 Feb 2026 23:31:48 +0800 [thread overview]
Message-ID: <c985a8ed-37ad-415e-b7b4-18a66b4da3fe@linux.dev> (raw)
In-Reply-To: <64f3a75a-30ff-4bee-833c-be5dba05f72b@intel.com>
On 2026/2/5 23:09, Dave Hansen wrote:
> On 2/5/26 07:01, Lance Yang wrote:
>> So for now, neither approach looks good: tracking on the read side adss
>> cost to GUP-fast, and syncing on the write side e.g. synchronize_rcu()
>> is too slow on large systems.
>
> Which of the writers truly *need* synchronize_rcu()?
>
> What are they doing with the memory that they can't move forward unless
> it's quiescent *now*?
Without IPIs or synchronize_rcu(), IIUC, we have no way to know if there
are ongoing concurrent lockless page-table walks — the walkers just disable
IRQs and walk.
next prev parent reply other threads:[~2026-02-05 15:32 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-02 7:45 [PATCH v4 0/3] targeted TLB sync IPIs for lockless page table walkers Lance Yang
2026-02-02 7:45 ` [PATCH v4 1/3] mm: use targeted IPIs for TLB sync with " Lance Yang
2026-02-02 9:42 ` Peter Zijlstra
2026-02-02 12:14 ` Lance Yang
2026-02-02 12:51 ` Peter Zijlstra
2026-02-02 13:23 ` Lance Yang
2026-02-02 13:42 ` Peter Zijlstra
2026-02-02 14:28 ` Lance Yang
2026-02-02 16:20 ` Dave Hansen
2026-02-02 11:37 ` kernel test robot
2026-02-03 23:49 ` kernel test robot
2026-02-02 7:45 ` [PATCH v4 2/3] mm: switch callers to tlb_remove_table_sync_mm() Lance Yang
2026-02-02 7:45 ` [PATCH v4 3/3] x86/tlb: add architecture-specific TLB IPI optimization support Lance Yang
2026-02-25 20:11 ` Sean Christopherson
2026-02-26 11:37 ` Lance Yang
2026-02-26 18:24 ` Sean Christopherson
2026-03-01 6:56 ` Lance Yang
2026-02-02 9:54 ` [PATCH v4 0/3] targeted TLB sync IPIs for lockless page table walkers Peter Zijlstra
2026-02-02 11:00 ` [PATCH v4 0/3] targeted TLB sync IPIs for lockless page table Lance Yang
2026-02-02 12:50 ` Peter Zijlstra
2026-02-02 12:58 ` Lance Yang
2026-02-02 13:07 ` Lance Yang
2026-02-02 13:37 ` Peter Zijlstra
2026-02-02 14:37 ` Lance Yang
2026-02-02 15:09 ` Peter Zijlstra
2026-02-02 15:52 ` Lance Yang
2026-02-05 13:25 ` David Hildenbrand (Arm)
2026-02-05 15:01 ` Lance Yang
2026-02-05 15:05 ` David Hildenbrand (Arm)
2026-02-05 15:28 ` Lance Yang
2026-02-05 15:09 ` Dave Hansen
2026-02-05 15:31 ` Lance Yang [this message]
2026-02-05 15:41 ` Dave Hansen
2026-02-05 16:30 ` Lance Yang
2026-02-05 16:46 ` David Hildenbrand (Arm)
2026-02-05 16:48 ` Matthew Wilcox
2026-02-05 17:06 ` David Hildenbrand (Arm)
2026-02-05 18:36 ` Dave Hansen
2026-02-05 22:49 ` David Hildenbrand (Arm)
2026-02-05 21:30 ` David Hildenbrand (Arm)
2026-02-05 17:00 ` Dave Hansen
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