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Thu, 16 Oct 2025 17:55:56 -0700 (PDT) Date: Fri, 17 Oct 2025 00:55:55 +0000 From: Wei Yang To: Wei Yang Cc: akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org Subject: Re: [Patch v2 2/2] mm/huge_memory: Optimize and simplify __split_unmapped_folio() logic Message-ID: <20251017005555.snztmz6hawkcwkpk@master> Reply-To: Wei Yang References: <20251016004613.514-1-richard.weiyang@gmail.com> <20251016004613.514-3-richard.weiyang@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251016004613.514-3-richard.weiyang@gmail.com> User-Agent: NeoMutt/20170113 (1.7.2) X-Stat-Signature: 9w4wemusjdo68yswm3hzskrzranoy6bc X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 75FF81A000A X-HE-Tag: 1760662558-737525 X-HE-Meta: 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 V2PoxqWi 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 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, Oct 16, 2025 at 12:46:13AM +0000, Wei Yang wrote: >Existing __split_unmapped_folio() code splits the given folio and update >stats, but it is complicated to understand. > >After simplification, __split_unmapped_folio() directly calculate and >update the folio statistics upon a successful split: > >* All resulting folios are @split_order. > >* The number of new folios are calculated directly from @old_order > and @split_order. > >* The folio for the next split is identified as the one containing > @split_at. > >* An xas_try_split() error is returned directly without worrying > about stats updates. @Andrew >From David and Zi comment, there is little change in change log. Would you mind helping update it? Below is the updated version. --- Existing __split_unmapped_folio() code splits the given folio and updates stats, but it is complicated to understand. After simplification, __split_unmapped_folio() directly calculates and updates the folio statistics upon a successful split: * All resulting folios are @split_order. * The number of new folios are calculated directly from @old_order and @split_order. * The folio for the next split is identified as the one containing @split_at. * Stats fixup is no longer needed for an xas_try_split() error, since since we now update the stats only after a successful split. -- Wei Yang Help you, Help me