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d=pankajraghav.com; s=MBO0001; t=1718004424; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=6iGob73/+SiPz4izhI7kTGZht0v2bPSc+GBGKwV0QDw=; b=An+Uh04344BjAG9Mk2nqabnGvtZ/+hXx1GPI0dI1WE8555DgD9yowev7iNOBrjihzcDVwd zGpq4FEZeEBpGok+5jATEJk0VeV6GOVwR/biqfE8HlOetnD2uKNbcQQLIrvK/h1vDDIOVx k2oIvMSRrHm+VFaMmzXI0sIvSYCL5GI4PgiWUoVsK2ijHTwrByUjV/sbIljXS5Ro6Q6gs9 vzHkJ3HBKg3av+1TQUo7cMYppmB8lYKDL1P2VshdRS4VxBlsXChLKCl4IVXAgUDOqOMRTr QWiW4grDV6XL1fiCvfKX3Cp189+GzybvBLGD6dc0rnZHL8waLJoeUrvS32L0RQ== Date: Mon, 10 Jun 2024 07:26:57 +0000 From: "Pankaj Raghav (Samsung)" To: Zi Yan Cc: willy@infradead.org, david@fromorbit.com, djwong@kernel.org, chandan.babu@oracle.com, brauner@kernel.org, akpm@linux-foundation.org, mcgrof@kernel.org, linux-mm@kvack.org, hare@suse.de, linux-kernel@vger.kernel.org, yang@os.amperecomputing.com, linux-xfs@vger.kernel.org, p.raghav@samsung.com, linux-fsdevel@vger.kernel.org, hch@lst.de, gost.dev@samsung.com, cl@os.amperecomputing.com, john.g.garry@oracle.com Subject: Re: [PATCH v7 05/11] mm: split a folio in minimum folio order chunks Message-ID: <20240610072657.erdzkedvbzj3gohu@quentin> References: <20240607145902.1137853-1-kernel@pankajraghav.com> <20240607145902.1137853-6-kernel@pankajraghav.com> <75CCE180-EC90-4BDC-B5D8-0ED1B710BE49@nvidia.com> <20240607203026.zj3akxdjeykchnnf@quentin> <45567EBA-5856-4BBC-8C02-EAE03A676B94@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45567EBA-5856-4BBC-8C02-EAE03A676B94@nvidia.com> X-Stat-Signature: wtmtjspzh36pwsbabdi9jkm3x187wq5n X-Rspamd-Queue-Id: 82EDE4000E X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1718004429-898749 X-HE-Meta: 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 FcmxZZEY T18Hj8QacYQA78eLC9YZjajCtyypbrpwxMfybMCAv+fYmXhHHttUzoZxpkAiGCwAmVwaOm/v31Z8X/RQGx4CsfdLJQW7YeWq8TzQ+vyf69Gr+YEH6Xy38W3IAgbYrX3sWn1fVyDBYX+rx/XnVoxDS9Ce3QtRVdyf5/VBMmCfY+wF/KV/Ob7mJbytPLXuKoVvoKGecMNZipUeZHh0= 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 Fri, Jun 07, 2024 at 04:51:04PM -0400, Zi Yan wrote: > On 7 Jun 2024, at 16:30, Pankaj Raghav (Samsung) wrote: > >>> + if (!folio->mapping) { > >>> + count_vm_event(THP_SPLIT_PAGE_FAILED); > >> > >> You should only increase this counter when the input folio is a THP, namely > >> folio_test_pmd_mappable(folio) is true. For other large folios, we will > >> need a separate counter. Something like MTHP_STAT_FILE_SPLIT_FAILED. > >> See enum mthp_stat_item in include/linux/huge_mm.h. > >> > > Hmm, but we don't have mTHP support for non-anonymous memory right? In > > that case it won't be applicable for file backed memory? > > Large folio support in page cache precedes mTHP (large anonymous folio), > thanks to willy's work. mTHP is more like a subset of large folio. > There is no specific counters for page cache large folio. If you think > it is worth tracking folios with orders between 0 and 9 (exclusive), > you can add counters. Matthew, what is your take on this? Got it. I think this is out of scope for this series but something we could consider as a future enhancement? In any case, we need to decide whether we need to count truncation as a VM event or not.