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Fri, 8 May 2026 18:48:54 -0400 (EDT) Date: Fri, 8 May 2026 23:48:53 +0100 From: Kiryl Shutsemau To: Andrew Morton Cc: rppt@kernel.org, peterx@redhat.com, david@kernel.org, ljs@kernel.org, surenb@google.com, vbabka@kernel.org, Liam.Howlett@oracle.com, ziy@nvidia.com, corbet@lwn.net, skhan@linuxfoundation.org, seanjc@google.com, pbonzini@redhat.com, jthoughton@google.com, aarcange@redhat.com, sj@kernel.org, usama.arif@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v2 00/14] userfaultfd: working set tracking for VM guest memory Message-ID: References: <20260508103220.aa46427b6f4c5d0247d2afb0@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260508103220.aa46427b6f4c5d0247d2afb0@linux-foundation.org> X-Stat-Signature: w7cniy5ho74911r8tmaimnhydj69tfh5 X-Rspam-User: X-Rspamd-Queue-Id: 4CCBD140005 X-Rspamd-Server: rspam07 X-HE-Tag: 1778280537-841656 X-HE-Meta: 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 d/p6nDQw kOYyWEK+iPEWfAKMNM3vMuEr3nEHzmOnaEhuKDHbSQ7viti6DDVHT3mnyn6EJWS/efFV1jWYucDdb/HNuTmcYGTSZVZnXnp7RLg0jiEdGzvX6OTzBPvYhTi+Gk/amPYXtqPODvzqXeIlh25r+QPKjVaoqChqvsR+TeN1skkdi76aflUk4i1xOTSLww+WNbL71YPiKmoE+3CjcuI557MrMGomq0gbdHLj+VAbnFGisKu1MMePvQZDUa9XU4ghLz40/vmpN6AWPpjoETlgUJZlLNeGNNpWjMAF5Ob4oV/RE+iUw6S8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, May 08, 2026 at 10:32:20AM -0700, Andrew Morton wrote: > On Fri, 8 May 2026 16:55:12 +0100 "Kiryl Shutsemau (Meta)" wrote: > > > This series adds userfaultfd support for tracking the working set of > > VM guest memory, so a VMM can identify cold pages and evict them to > > tiered or remote storage. > > > > v1: https://lore.kernel.org/all/20260427114607.4068647-1-kas@kernel.org/ > > Thanks. I'll duck v2 for now, await more review. Sure. > > Assisted-by: Claude:claude-opus-4-6 > > For my education, and perhaps for others: can you please explain how > you used Claude in the preparation of this series? I'm no expert by any means, but here's how I used it here. For this particular project there was quite a bit of path-finding. I had a phase where I bounced ideas off Claude. It helped me understand the problem space better and formulate possible solutions. Rubber ducking on steroids. Once it's clear _what_ to do, we formulate a plan on _how_. It also involves back and forth. Once the plan was done, I gave the go-ahead on executing it. Userfaultfd already had a test suite, and it was extended to cover the new functionality. I have some scripts to build the kernel and run it in a VM. Claude knows how to use them, so at the end of plan execution I had a functional feature. Then the review phase. The most time-consuming and draining part. I carefully reviewed all patches. At this stage I use Claude as an editor. Some of the changes I asked for required substantial rework of the whole patchset, and I had to start the review from scratch. A good test suite and build-test harness help to keep the whole thing from falling apart. It took me quite a few review rounds before I was happy with the result. Maybe between 8 and 10. I think better instructions can cut this number down. And I need to rethink how I do the review. Reading the git log in parallel with examining the code in the editor and giving instructions to Claude is not very ergonomic. There's room for improvement. Once I was happy with the patchset to give it Signed-off-by, I ran it through Chris' review prompts several times, addressing the issues. I hope it is helpful. I would also be glad if other folks shared their workflow. There is probably a better way to achieve the same result. I am new to the game. -- Kiryl Shutsemau / Kirill A. Shutemov