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Mon, 20 Apr 2026 19:01:55 -0700 (PDT) Received: from pve-server ([49.205.216.49]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b5fa9ff3b4sm149129515ad.2.2026.04.20.19.01.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2026 19:01:54 -0700 (PDT) From: Ritesh Harjani (IBM) To: Salvatore Dipietro Cc: Matthew Wilcox , abuehaze@amazon.de, alisaidi@amazon.com, blakgeof@amazon.com, brauner@kernel.org, dipietro.salvatore@gmail.com, djwong@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 1/1] iomap: avoid compaction for costly folio order allocation In-Reply-To: Date: Tue, 21 Apr 2026 06:46:19 +0530 Message-ID: References: <20260420163328.22104-1-dipiets@amazon.it> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Matthew Wilcox writes: > On Mon, Apr 20, 2026 at 04:33:28PM +0000, Salvatore Dipietro wrote: >> I have submitted a v2 of the patch based on Ritesh's suggestion. >> https://lore.kernel.org/linux-mm/20260420161404.642-1-dipiets@amazon.it/T/#u > > ... but without linking back to this thread, so nobody who was exposed > to that thread for the first time knows about this one. That's poor form. Yup. Also, given the Maintainers (willy, Christoph, Dave) shown their dis-interest in taking the patch in it's current form, the right way is to get back with performance data with both the approaches (which we were discussing) and first get the consensus from everyone, before proposing this as a patch :). Having said that, we do care if a genuine performance issue gets reported. In that context, I wanted to understand your setup a bit from memory fragmentation perspective. Are you trying to simulate memory fragmentation and then benchmarking? Or was this problem hitting when you run simply run the reproduction steps mentioned in your cover letter? BTW - I was following the other thread too where PREEMPT_LAZY problem was getting discussed. And from what I understood, you mentioned [1] enabling THP on the system made that problem go away. Also it looks like enabling THP is the right thing to do for this kind of workload. Does that also mean enabling THP fixed this problem too? Do you still hit memory fragmentation and/or similar throughput drop w/o this fix after you enable THP? It will be good to know those details too please. [1]: https://lore.kernel.org/all/20260403191942.21410-1-dipiets@amazon.it/T/#md88ca4258766e897e432df85874d197db476c7d1 -ritesh