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From: Byungchul Park <byungchul@sk.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	kernel_team@skhynix.com, akpm@linux-foundation.org,
	ying.huang@intel.com, vernhao@tencent.com,
	mgorman@techsingularity.net, hughd@google.com,
	willy@infradead.org, david@redhat.com, peterz@infradead.org,
	luto@kernel.org, tglx@linutronix.de, mingo@redhat.com,
	bp@alien8.de, dave.hansen@linux.intel.com, rjgolo@gmail.com
Subject: Re: [RFC PATCH v12 00/26] LUF(Lazy Unmap Flush) reducing tlb numbers over 90%
Date: Fri, 21 Feb 2025 08:23:29 +0900	[thread overview]
Message-ID: <20250220232329.GA39373@system.software.com> (raw)
In-Reply-To: <8accbd91-ca59-43f8-b190-7e1ac3df5e11@intel.com>

On Thu, Feb 20, 2025 at 07:15:44AM -0800, Dave Hansen wrote:
> On 2/19/25 21:20, Byungchul Park wrote:
> > I'm posting the latest version so that anyone can try luf mechanism if
> > wanted by any chance.  However, I tagged RFC again because there are
> > still issues that should be resolved to merge to mainline:
> 
> I don't see anything fundamentally different here from the last 11
> versions. I think the entire approach is dangerous and basically makes
> things impossible to debug. It's not clear that some of the failure
> scenarios that I've brought up in the past have actually been fixed.

Respect your opinion.

> What I've said here still stands:
> 
> > https://lore.kernel.org/all/fab1dd64-c652-4160-93b4-7b483a8874da@intel.com/
> 
> > I think tglx would call all of this "tinkering".  The approach to this
> > series is to "fix" narrow, specific cases that reviewers point out, make
> > it compile, then send it out again, hoping someone will apply it.
> > 
> > So, for me, until the approach to this series changes: NAK, for x86.
> > Andrew, please don't take this series.  Or, if you do, please drop the
> > patch enabling it on x86.
> 
> I think I'd also like to stop being cc'd on this. If LUF is merged into

I will un-cc you from the next spin.

	Byungchul

> mainline and proven to work on arm64 or riscv for a year, I'd be happy
> to take another look at enabling it on x86. I think that's just about
> the only thing that would make me reconsider.


      parent reply	other threads:[~2025-02-20 23:23 UTC|newest]

Thread overview: 102+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-20  5:20 Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 01/26] x86/tlb: add APIs manipulating tlb batch's arch data Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 02/26] arm64/tlbflush: " Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 03/26] riscv/tlb: " Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 04/26] x86/tlb, riscv/tlb, mm/rmap: separate arch_tlbbatch_clear() out of arch_tlbbatch_flush() Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 05/26] mm/buddy: make room for a new variable, luf_key, in struct page Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 06/26] mm: move should_skip_kasan_poison() to mm/internal.h Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 07/26] mm: introduce luf_ugen to be used as a global timestamp Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 08/26] mm: introduce luf_batch to be used as hash table to store luf meta data Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 09/26] mm: introduce API to perform tlb shootdown on exit from page allocator Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 10/26] mm: introduce APIs to check if the page allocation is tlb shootdownable Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 11/26] mm: deliver luf_key to pcp or buddy on free after unmapping Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 12/26] mm: delimit critical sections to take off pages from pcp or buddy alloctor Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 13/26] mm: introduce pend_list in struct free_area to track luf'd pages Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 14/26] mm/rmap: recognize read-only tlb entries during batched tlb flush Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 15/26] fs, filemap: refactor to gather the scattered ->write_{begin,end}() calls Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 16/26] mm: implement LUF(Lazy Unmap Flush) defering tlb flush when folios get unmapped Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 17/26] x86/tlb, riscv/tlb, arm64/tlbflush, mm: remove cpus from tlb shootdown that already have been done Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 18/26] mm/page_alloc: retry 3 times to take pcp pages on luf check failure Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 19/26] mm: skip luf tlb flush for luf'd mm that already has been done Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 20/26] mm, fs: skip tlb flushes for luf'd filemap " Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 21/26] mm: perform luf tlb shootdown per zone in batched manner Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 22/26] mm/page_alloc: not allow to tlb shootdown if !preemptable() && non_luf_pages_ok() Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 23/26] mm: separate move/undo parts from migrate_pages_batch() Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 24/26] mm/migrate: apply luf mechanism to unmapping during migration Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 25/26] mm/vmscan: apply luf mechanism to unmapping during folio reclaim Byungchul Park
2025-02-20  5:20 ` [RFC PATCH v12 26/26] mm/luf: implement luf debug feature Byungchul Park
2025-02-20 10:32 ` [RFC PATCH v12 00/26] LUF(Lazy Unmap Flush) reducing tlb numbers over 90% Hillf Danton
2025-02-20 10:51   ` Byungchul Park
2025-02-20 11:09   ` Byungchul Park
2025-02-20 11:49     ` Hillf Danton
2025-02-20 12:20       ` Byungchul Park
2025-02-20 12:40       ` Byungchul Park
2025-02-20 13:54       ` Matthew Wilcox
2025-02-20 15:09         ` Steven Rostedt
2025-02-20 22:53           ` Kent Overstreet
2025-02-20 23:05             ` Steven Rostedt
2025-02-20 23:21               ` Kent Overstreet
2025-02-20 23:25           ` Hillf Danton
2025-02-20 23:44             ` Steven Rostedt
     [not found]             ` <20250221230556.2479-1-hdanton@sina.com>
2025-02-22  7:16               ` Greg KH
     [not found]               ` <20250222101100.2531-1-hdanton@sina.com>
2025-02-22 13:57                 ` Greg KH
2025-03-10 23:24       ` Dan Williams
2025-03-10 23:53         ` Barry Song
     [not found]       ` <20250619134922.1219-1-hdanton@sina.com>
2025-06-20 17:00         ` Dan Williams
2025-02-20 15:15 ` Dave Hansen
2025-02-20 15:29   ` Vlastimil Babka
2025-02-20 23:37     ` Byungchul Park
2025-02-26 11:30       ` RFC v12 rebased on v6.14-rc4 Byungchul Park
2025-02-26 12:03         ` [RFC PATCH v12 based on v6.14-rc4 01/25] x86/tlb: add APIs manipulating tlb batch's arch data Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 02/25] arm64/tlbflush: " Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 03/25] riscv/tlb: " Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 04/25] x86/tlb, riscv/tlb, mm/rmap: separate arch_tlbbatch_clear() out of arch_tlbbatch_flush() Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 05/25] mm/buddy: make room for a new variable, luf_key, in struct page Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 06/25] mm: move should_skip_kasan_poison() to mm/internal.h Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 07/25] mm: introduce luf_ugen to be used as a global timestamp Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 08/25] mm: introduce luf_batch to be used as hash table to store luf meta data Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 09/25] mm: introduce API to perform tlb shootdown on exit from page allocator Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 10/25] mm: introduce APIs to check if the page allocation is tlb shootdownable Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 11/25] mm: deliver luf_key to pcp or buddy on free after unmapping Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 12/25] mm: delimit critical sections to take off pages from pcp or buddy alloctor Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 13/25] mm: introduce pend_list in struct free_area to track luf'd pages Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 14/25] mm/rmap: recognize read-only tlb entries during batched tlb flush Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 15/25] fs, filemap: refactor to gather the scattered ->write_{begin,end}() calls Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 16/25] mm: implement LUF(Lazy Unmap Flush) defering tlb flush when folios get unmapped Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 17/25] x86/tlb, riscv/tlb, arm64/tlbflush, mm: remove cpus from tlb shootdown that already have been done Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 18/25] mm/page_alloc: retry 3 times to take pcp pages on luf check failure Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 19/25] mm: skip luf tlb flush for luf'd mm that already has been done Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 20/25] mm, fs: skip tlb flushes for luf'd filemap " Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 21/25] mm: perform luf tlb shootdown per zone in batched manner Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 22/25] mm/page_alloc: not allow to tlb shootdown if !preemptable() && non_luf_pages_ok() Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 23/25] mm/migrate: apply luf mechanism to unmapping during migration Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 24/25] mm/vmscan: apply luf mechanism to unmapping during folio reclaim Byungchul Park
2025-02-26 12:03           ` [RFC PATCH v12 based on v6.14-rc4 25/25] mm/luf: implement luf debug feature Byungchul Park
2025-02-26 11:33       ` RFC v12 rebased on mm-unstable as of Feb 21, 2025 Byungchul Park
2025-02-26 12:01         ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 01/25] x86/tlb: add APIs manipulating tlb batch's arch data Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 02/25] arm64/tlbflush: " Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 03/25] riscv/tlb: " Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 04/25] x86/tlb, riscv/tlb, mm/rmap: separate arch_tlbbatch_clear() out of arch_tlbbatch_flush() Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 05/25] mm/buddy: make room for a new variable, luf_key, in struct page Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 06/25] mm: move should_skip_kasan_poison() to mm/internal.h Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 07/25] mm: introduce luf_ugen to be used as a global timestamp Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 08/25] mm: introduce luf_batch to be used as hash table to store luf meta data Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 09/25] mm: introduce API to perform tlb shootdown on exit from page allocator Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 10/25] mm: introduce APIs to check if the page allocation is tlb shootdownable Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 11/25] mm: deliver luf_key to pcp or buddy on free after unmapping Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 12/25] mm: delimit critical sections to take off pages from pcp or buddy alloctor Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 13/25] mm: introduce pend_list in struct free_area to track luf'd pages Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 14/25] mm/rmap: recognize read-only tlb entries during batched tlb flush Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 15/25] fs, filemap: refactor to gather the scattered ->write_{begin,end}() calls Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 16/25] mm: implement LUF(Lazy Unmap Flush) defering tlb flush when folios get unmapped Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 17/25] x86/tlb, riscv/tlb, arm64/tlbflush, mm: remove cpus from tlb shootdown that already have been done Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 18/25] mm/page_alloc: retry 3 times to take pcp pages on luf check failure Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 19/25] mm: skip luf tlb flush for luf'd mm that already has been done Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 20/25] mm, fs: skip tlb flushes for luf'd filemap " Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 21/25] mm: perform luf tlb shootdown per zone in batched manner Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 22/25] mm/page_alloc: not allow to tlb shootdown if !preemptable() && non_luf_pages_ok() Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 23/25] mm/migrate: apply luf mechanism to unmapping during migration Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 24/25] mm/vmscan: apply luf mechanism to unmapping during folio reclaim Byungchul Park
2025-02-26 12:01           ` [RFC PATCH v12 based on mm-unstable as of Feb 21, 2025 25/25] mm/luf: implement luf debug feature Byungchul Park
2025-02-22  1:14     ` [RFC PATCH v12 00/26] LUF(Lazy Unmap Flush) reducing tlb numbers over 90% Shakeel Butt
2025-02-20 23:23   ` Byungchul Park [this message]

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