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AJvYcCVVkHR08CP9R7vyEelsGO0LBXRcuONwMWTpgYbQ51aGJiCJXGpqdoAZhQ+Bzqy/rJTljeWqB09hmw==@kvack.org X-Gm-Message-State: AOJu0Yw6bKH6O0usy9e70CnrujskoLoZYGbnsSbYSMTHO4jXGoK+n6DD WjCIG2F0IstdQNZxxvlML9CYjii6yTgNyQUqXPPBzJMKL2kiVFRNrofgaHO2sZBwLCr4T3q9ozI qi6lJEJLCNtB2ZshDQ+wcgZjUtl2fJu8942PN1i7HgA== X-Gm-Gg: ASbGncu2KNXUEJxdiK/vDUpOPsS1d3P2WyDm0/4y+MrRdo17KaLB5RsYExQj4x7bU6A HXXgOie2ZrmoXOmrPTafnNaMpW+/sk0jjkpqp4uIgvwKHTDl6DBjAXcPmBDcqj1b65WHTw5CVAV IMa0L7XLJXrvByhM6mgnk46RvRMEfB9feIQQ== X-Google-Smtp-Source: AGHT+IEbYc+4S5SR2VuN6dHgpiMYP2OjzGQER1NiI1iefPsAH+wNn3K2+G95ErnxaSqP75RCwC6IjiRQYZ5GzLKv/98= X-Received: by 2002:a05:690c:14:b0:708:bfc6:c7cd with SMTP id 00721157ae682-70ca797c8f2mr141952157b3.6.1747633172467; Sun, 18 May 2025 22:39:32 -0700 (PDT) MIME-Version: 1.0 References: <20250414013627.GA9161@system.software.com> <20250414015207.GA50437@system.software.com> <20250414163002.166d1a36@kernel.org> In-Reply-To: From: Ilias Apalodimas Date: Mon, 19 May 2025 08:38:55 +0300 X-Gm-Features: AX0GCFtOseuh1Qwexh3KTJNyXVhGEQU8_Vhw9OLuXa7HCysaP70bT9gQlbbQ9Ig Message-ID: Subject: Re: [RFC] shrinking struct page (part of page pool) To: Andrew Lunn Cc: Jakub Kicinski , Byungchul Park , willy@infradead.org, almasrymina@google.com, kernel_team@skhynix.com, 42.hyeyoo@gmail.com, linux-mm@kvack.org, hawk@kernel.org, netdev@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7BC0EC0006 X-Stat-Signature: s3opo4hwqro95333tju6r165wuuhn178 X-Rspam-User: X-HE-Tag: 1747633173-586120 X-HE-Meta: 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 YWyew1Oe f+F4FTOWOgeAwF9uWT1BJIm4WHpP7obuqmpGJju0KGULmymOpelSBPOhLpLEML2kTKMUNcCu99MasW6BZuSVqOk3PaXVldQQ3sdVnEbCgfO2ZFisH8XfSRKbwV+kC1sYvZC2MkmveLe4EQ0mQQ/VnXO/qJNEmOGdXWu9e775QdZdBu3rBBrp2aUTaKBnYtSI/OwsAjJ2cE6Xlm6pzEmlpOnCQWPLX6pmML7gc23AuzXIk8wFuChSyEGeP68h5DqOO2xD0 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: Hi Andrew Apologies for the late reply, On Sat, 10 May 2025 at 16:53, Andrew Lunn wrote: > > On Sat, May 10, 2025 at 10:02:59AM +0300, Ilias Apalodimas wrote: > > Hi Jakub > > > > [...] > > > > > > > > > > > > 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. > > > > > > I don't see any benefit from moving page pool to MM. It is quite > > > networking specific. But we can discuss this later. Moving code > > > is trivial, it should not be the initial focus. > > > > Random thoughts here until I look at the patches. > > The concept of devices doing DMA + recycling the used buffer > > transcends networking. > > Do you know of any other subsystem which takes a page, splits it into > two, and then uses each half independently for DMA and recycling. A > typical packet is 1514 octets, so you can get two in a page. No, but OTOH the recycling is not somehow bound to having multiple fragments of a page. So I assumed more subsystems would benefit from not constantly re-allocating and re-mapping pages Thanks /Ilias > > Andrew