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From: Shakeel Butt To: Vlastimil Babka , sj@kernel.org Cc: Dave Hansen , Byungchul Park , 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% Message-ID: <6cdstauw4b64gpi6xxmuumuzvkgtjpczienh7neogqjlarqilv@eujvenmk2uyh> References: <20250220052027.58847-1-byungchul@sk.com> <8accbd91-ca59-43f8-b190-7e1ac3df5e11@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 9A4E6100002 X-Stat-Signature: 3riux5g48txjjjuptk8ns9ragnt8k3oy X-Rspam-User: X-HE-Tag: 1740186900-44812 X-HE-Meta: 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 haDR3vVc QbxAFpbeVJ0hYrWn5jx1+lATUHPfKNe6bfuNHLxohCIAFH2s3QJFd9F8Nbaoe7p8Xm6zO4pvMpFB5CFUHKZmNajAPeWff5QZu4X79FwcWJdtkKGQZiHTFUw6LvF6CzBuRtGEjMZW5gMXQL6wHdGvQB7qMhM7JYaWQJe+6U1Ln4w7EWPOMsgnROTZ3Nw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Feb 20, 2025 at 04:29:51PM +0100, Vlastimil Babka wrote: > On 2/20/25 16:15, 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. > > Yes, and it's still an invasive change to the buddy allocator. > IIRC at Plumbers the opinion in the audience was that there might be ways to > improve the batching on unmap to reduce the flushes without such an invasive > and potentially dangerous change? Has that been investigated? > I know SJ (CCed) is working on making TLB flush batching work for process_madvise().