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bh=hiK/h1RoTIJHOtBagghUKJEj3PPDrNJwRwcrNwvq634=; b=jxbhQA7e8foVh1VcyYI78hjCUnBix6KBEmi5RoYJm6iaxZCi6otBM7uIntpK9blQRhConp FqAVz8dt9VAWGW2PHiecHYXvOWl2j3YIlhqGghKooJdTTtXQyzjUfLzXFWBIdZKutNN9JQ WQBhWZInSfjiI+rmcxWWtCFloaDgzao= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf04.hostedemail.com: domain of byungchul@sk.com designates 166.125.252.92 as permitted sender) smtp.mailfrom=byungchul@sk.com X-AuditID: a67dfc5b-681ff7000002311f-e2-67ff3f6a8e1c Date: Wed, 16 Apr 2025 14:25:57 +0900 From: Byungchul Park To: "Vishal Moola (Oracle)" Cc: willy@infradead.org, ilias.apalodimas@linaro.org, almasrymina@google.com, kernel_team@skhynix.com, 42.hyeyoo@gmail.com, linux-mm@kvack.org Subject: Re: [RFC] shrinking struct page (part of page pool) Message-ID: <20250416052557.GC39145@system.software.com> References: <20250414013627.GA9161@system.software.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrPLMWRmVeSWpSXmKPExsXC9ZZnoW62/f90g10zmSwm9hhYrP5RYdHb 8pvZ4t6a/6wW6/fdYLX4/WMOmwObx85Zd9k9Fmwq9di8Qstj06dJ7B53ru1hC2CN4rJJSc3J LEst0rdL4MpoPdfDWPBcuOLswrPMDYy9/F2MnBwSAiYSF44/YYGxF33fwgxiswioSsz//ZEN xGYTUJe4ceMnWFwEpOb1TaB6Lg5mgUmMEk3XPrODJIQFbCS2/5jLCmLzClhI7Hx5gBHEFhII lnjb9p0FIi4ocXImxDJmAS2JG/9eMnUxcgDZ0hLL/3GAhDkF1CR23ToPtktUQFniwLbjTCC7 JAQWsElsW/CKGeJQSYmDK26wTGAUmIVk7CwkY2chjF3AyLyKUSgzryw3MTPHRC+jMi+zQi85 P3cTIzCYl9X+id7B+OlC8CFGAQ5GJR7eiPh/6UKsiWXFlbmHGCU4mJVEeM+ZA4V4UxIrq1KL 8uOLSnNSiw8xSnOwKInzGn0rTxESSE8sSc1OTS1ILYLJMnFwSjUwTlx4ZOqmr8s5uDIdV2bo 7XLfbrVjz8upRldjn11edEPp+TJe8zk8K6t8eXakuXd594m89XQ+87W7V+X2jll7frziuBMi +qzz44Nn8/7dP3LVV1ZK0a5g06MY39dTI98dPrfK91dZsZVf+Zs/t+002+NkvJ/82jV5wdwt QXsTDPUTN7X9jA/6Y6nEUpyRaKjFXFScCADeXhmmYgIAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrGLMWRmVeSWpSXmKPExsXC5WfdrJtl/z/d4P1CM4uJPQYWq39UWPS2 /Ga2ODz3JKvFvTX/WS3W77vBavH7xxw2B3aPnbPusnss2FTqsXmFlsemT5PYPe5c28PmsfjF B6YAtigum5TUnMyy1CJ9uwSujNZzPYwFz4Urzi48y9zA2MvfxcjJISFgIrHo+xZmEJtFQFVi /u+PbCA2m4C6xI0bP8HiIiA1r2+ydDFycTALTGKUaLr2mR0kISxgI7H9x1xWEJtXwEJi58sD jCC2kECwxNu27ywQcUGJkzOfgNnMAloSN/69ZOpi5ACypSWW/+MACXMKqEnsunUebJeogLLE gW3HmSYw8s5C0j0LSfcshO4FjMyrGEUy88pyEzNzTPWKszMq8zIr9JLzczcxAkNzWe2fiTsY v1x2P8QowMGoxMMbEf8vXYg1say4MvcQowQHs5II7zlzoBBvSmJlVWpRfnxRaU5q8SFGaQ4W JXFer/DUBCGB9MSS1OzU1ILUIpgsEwenVAPj0f1Vjbs3n3lSI/PpxK5PSeIfCmsOTMnKFg97 0nztWUDE48fT1xxqnC5hbpNZEZX6MZMzZ/N+P+6dFlqVrAu0XY9O2HrmQHOg0Fcbk8crFfwc GcWrb2xvk+LoinjCuCbqpjn7hLq5W/d9S2LkfOTGltsrOUt4kv+sA8WiF4vMNeqbmEUm/Zuv xFKckWioxVxUnAgAycQg9EkCAAA= X-CFilter-Loop: Reflected X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: B3C2240007 X-Stat-Signature: s5pf87ifdwh1itgh3pi6wg7n1rztb3qy X-Rspam-User: X-HE-Tag: 1744781166-796644 X-HE-Meta: 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 bLs0raSZ OLU+8l7Gd4b//TcS/J8DSzDHLcMyzwor7mmeeINIY8QuRhnubN1hOq3fnfLxuuigl+1ZlLCKqnOpuT8WCPKXJmw1Vxw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.036181, 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 Tue, Apr 15, 2025 at 04:22:31PM -0700, Vishal Moola (Oracle) wrote: > On Mon, Apr 14, 2025 at 10:36:27AM +0900, Byungchul Park wrote: > > Hi guys, > > > > I'm looking at network's page pool code to help 'shrinking struct page' > > project by Matthew Wilcox. See the following link: > > > > https://kernelnewbies.org/MatthewWilcox/Memdescs/Path > > Thanks for looking at this! > > > My first goal is to remove fields for page pool from struct page like: > > > > struct { /* page_pool used by netstack */ > > /** > > * @pp_magic: magic value to avoid recycling non > > * page_pool allocated pages. > > */ > > unsigned long pp_magic; > > struct page_pool *pp; > > unsigned long _pp_mapping_pad; > > unsigned long dma_addr; > > atomic_long_t pp_ref_count; > > }; > > > > Fortunately, many prerequisite works have been done by Mina but I guess > > he or she has done it for other purpose than 'shrinking struct page'. > > > > I'd like to just finalize the work so that the fields above can be > > removed from struct page. However, I need to resolve a curiousity > > before starting. > > I have a blog that walks you through what I focused on when making > ptdescs. It would benefit you to look at: > > https://blogs.oracle.com/linux/post/introducing-memdesc Hi bro, Thank you for sharing the blog. Byungchul > I'll need to start looking into the networking code before I can > offer any opinions about the specifics of the descriptor though. > > > Network guys already introduced a sperate strcut, struct net_iov, > > to overlay the interesting fields. However, another separate struct > > for system memory might be also needed e.g. struct bump so that > > struct net_iov and struct bump can be overlayed depending on the > > source: > > > > struct bump { > > unsigned long _page_flags; > > unsigned long bump_magic; > > struct page_pool *bump_pp; > > unsigned long _pp_mapping_pad; > > unsigned long dma_addr; > > atomic_long_t bump_ref_count; > > unsigned int _page_type; > > atomic_t _refcount; > > }; > > > > To netwrok guys, any thoughts on it? > > To Willy, do I understand correctly your direction? > > > > Plus, it's a quite another issue but I'm curious, that is, what do you > > guys think about moving the bump allocator(= page pool) code from > > network to mm? I'd like to start on the work once gathering opinion > > from both Willy and network guys. > > > > Byungchul > >