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Sun, 03 May 2026 07:15:31 -0700 (PDT) Date: Sun, 3 May 2026 15:15:28 +0100 From: Gregory Price To: Matthew Wilcox Cc: "Ritesh Harjani (IBM)" , linux-fsdevel , Amir Goldstein , Christian Brauner , Jan Kara , lsf-pc , Bharata B Rao , Donet Tom , Aboorva Devarajan , linux-mm@kvack.org, Ojaswin Mujoo Subject: Re: [LSF/MM/BPF BoF Session] Numa-Aware Placement for Page Cache Pages Message-ID: References: Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sun, May 03, 2026 at 12:00:48AM +0100, Matthew Wilcox wrote: > On Sat, May 02, 2026 at 03:57:19PM +0100, Gregory Price wrote: > > On Thu, Apr 30, 2026 at 02:15:19PM +0100, Matthew Wilcox wrote: > > > Ideally, no, the kernel should observe the task and get it right. > > > > Out of curiosity, a use case i've been exploring is something like > > > > fd = open() > > buf = mmap(fd, ...) > > mbind(buf, device_node) > > /* fault file pages directly onto device memory */ > > Could you be explicit what _kind_ of node you're talking about here? > My initial thought went to something like DAX where the node actually > contains persistent memory and the fd is a reference to some chunk > of that storage. But I don't think that's what you're referring to. > You might be thinking about a presentation of DRAM over the CXL fabric. > Or you might be thinking about memory presented by a graphics card > (perhaps over CXL, perhaps some other way). The meaning of "device > memory" has become thoroughly confused (thanks Jerome!) so I sincerely > don't know what you're talking about. > Ah, I can see how the language has moved over time. But yes a gpu with onboard memory presented as a NUMA node, or some other accelerator where the kernel is responsible for managing its memory (rather than a driver). Probably the use-case needs a bit more consideration before we go dangling new policies off the page cache - just chewing on ideas. ~Gregory