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imf24.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf24.hostedemail.com: domain of byungchul@sk.com designates 166.125.252.92 as permitted sender) smtp.mailfrom=byungchul@sk.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1740569632; a=rsa-sha256; cv=none; b=IidmqjXXNPxLYw7zP4z7K8XGNuA0V/Z2RAjywo5carTWjEjgxqRXhAUUH7pWcupR8i2by4 EpPINrcnJqQI6beuzHtt10LDDI1lFOC5GC1qq7YKQ0n6k39zJ4sn3JfQE/RsNXKMoDuU1h DeXDkbMnU+0eVdk4tssRmbErTODPrLo= X-AuditID: a67dfc5b-3c9ff7000001d7ae-2f-67befc1cc8a2 Date: Wed, 26 Feb 2025 20:33:43 +0900 From: Byungchul Park To: Vlastimil Babka Cc: Dave Hansen , 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, rjgolo@gmail.com Subject: RFC v12 rebased on mm-unstable as of Feb 21, 2025 Message-ID: <20250226113342.GB1935@system.software.com> References: <20250220052027.58847-1-byungchul@sk.com> <8accbd91-ca59-43f8-b190-7e1ac3df5e11@intel.com> <20250220233710.GB39373@system.software.com> MIME-Version: 1.0 Content-Type: text/plain; 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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. > > Didn't want.. but admit. > > > 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? > > Sure. I tried like, by holding those pages not freed until either no > one accesses the interesting pages or memory pressure is high. However, > unfortunately it was super hard to fix performance degradation by the > number of page reclaim increased due to the unfreed pages. > > > Also "Rebase on akpm/mm.git mm-unstable(5a7056135b) as of Nov 22, 2024." is > > very outdated at this point? > > Sorry for that. I will rebase and share. This is the same patch set but rebased on akpm/mm.git mm-unstable(f7ed46277aa) as of Feb 21, 2025. Byungchul > Byungchul > > > > Thanks, > > Vlastimil > > > > > 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 > > > 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. > > >