From: Dave Hansen <dave.hansen@intel.com>
To: Lance Yang <lance.yang@linux.dev>, Peter Zijlstra <peterz@infradead.org>
Cc: akpm@linux-foundation.org, david@kernel.org,
dave.hansen@linux.intel.com, ypodemsk@redhat.com,
hughd@google.com, will@kernel.org, aneesh.kumar@kernel.org,
npiggin@gmail.com, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, x86@kernel.org, hpa@zytor.com, arnd@arndb.de,
lorenzo.stoakes@oracle.com, ziy@nvidia.com,
baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com,
npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com,
baohua@kernel.org, shy828301@gmail.com, riel@surriel.com,
jannh@google.com, jgross@suse.com, seanjc@google.com,
pbonzini@redhat.com, boris.ostrovsky@oracle.com,
virtualization@lists.linux.dev, kvm@vger.kernel.org,
linux-arch@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, ioworker0@gmail.com
Subject: Re: [PATCH v4 1/3] mm: use targeted IPIs for TLB sync with lockless page table walkers
Date: Mon, 2 Feb 2026 08:20:13 -0800 [thread overview]
Message-ID: <be38af98-e344-4552-a77b-b5345135e382@intel.com> (raw)
In-Reply-To: <0f44dfb7-fce3-44c1-ab25-b013ba18a59b@linux.dev>
On 2/2/26 04:14, Lance Yang wrote:
>>> Note that the tracking adds ~3% latency to GUP-fast, as measured on a
>>> 64-core system.
>>
>> What architecture, and that is acceptable?
>
> x86-64.
>
> I ran ./gup_bench which spawns 60 threads, each doing 500k GUP-fast
> operations (pinning 8 pages per call) via the gup_test ioctl.
>
> Results for pin pages:
> - Before: avg 1.489s (10 runs)
> - After: avg 1.533s (10 runs)
>
> Given we avoid broadcast IPIs on large systems, I think this is a
> reasonable trade-off 🙂
I thought the big databases were really sensitive to GUP-fast latency.
They like big systems, too. Won't they howl when this finally hits their
testing?
Also, two of the "write" side here are:
* collapse_huge_page() (khugepaged)
* tlb_remove_table() (in an "-ENOMEM" path)
Those are quite slow paths, right? Shouldn't the design here favor
keeping gup-fast as fast as possible as opposed to impacting those?
next prev parent reply other threads:[~2026-02-02 16:20 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-02 7:45 [PATCH v4 0/3] targeted TLB sync IPIs for " 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 [this message]
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
2026-02-02 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
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=be38af98-e344-4552-a77b-b5345135e382@intel.com \
--to=dave.hansen@intel.com \
--cc=Liam.Howlett@oracle.com \
--cc=akpm@linux-foundation.org \
--cc=aneesh.kumar@kernel.org \
--cc=arnd@arndb.de \
--cc=baohua@kernel.org \
--cc=baolin.wang@linux.alibaba.com \
--cc=boris.ostrovsky@oracle.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=david@kernel.org \
--cc=dev.jain@arm.com \
--cc=hpa@zytor.com \
--cc=hughd@google.com \
--cc=ioworker0@gmail.com \
--cc=jannh@google.com \
--cc=jgross@suse.com \
--cc=kvm@vger.kernel.org \
--cc=lance.yang@linux.dev \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lorenzo.stoakes@oracle.com \
--cc=mingo@redhat.com \
--cc=npache@redhat.com \
--cc=npiggin@gmail.com \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=riel@surriel.com \
--cc=ryan.roberts@arm.com \
--cc=seanjc@google.com \
--cc=shy828301@gmail.com \
--cc=tglx@linutronix.de \
--cc=virtualization@lists.linux.dev \
--cc=will@kernel.org \
--cc=x86@kernel.org \
--cc=ypodemsk@redhat.com \
--cc=ziy@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox