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charset="UTF-8" X-Rspamd-Queue-Id: 83A521C000C X-Rspamd-Server: rspam03 X-Rspam-User: X-Stat-Signature: epngiz896agx1www6wtcu7nruocrbh73 X-HE-Tag: 1749575089-111504 X-HE-Meta: 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 uYjK9ydf qAbwFBWs3TH9LaMjhXMMpoFjm7JzXhqF2YhRARSdM7sGKxoeGdmDYywDUbQ2F1Zp4+HVyGB3NRHoBKLluoYirTOoD/ZqksUqkayZmgEl0k65BOGvjebyQH9tQ0s4NQ32SdnmMFoTufjMDvIY42JrvWqR3alIG/P7USk5Amo5niyWknfElOSEelNquw1sgWLia9+3ziLxPmKwUK9WLfXhFnnunlnYNwwOpNjV6GFtFUolhAVrMCE2h5YyvvkRwQqmq9rclnP43T0wrECNJpV5/Nra5kw== 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 Mar 13, 2025 at 6:11 PM UTC, Brendan Jackman wrote: > .:: Patchset overview Hey all, I have been down the pagetable mines lately trying to figure out a solution to the page cache issue (the 70% FIO degradatation [0]). I've got a prototype based on the idea I discussed at LSF/MM/BPF that's slowly coming together. My hope is that as soon as I can convincingly claim with a straight face that I know how to solve that problem, I can transition from mode into being a bit more visible with development iterations... [0] https://lore.kernel.org/linux-mm/20250129144320.2675822-1-jackmanb@google.com/ In the meantime, I am still provisionally planning to make the topic of this RFC the first [PATCH] series for ASI. Obviously before I can seriously ask Andrew to merge I'll also need to establish some consensus on the x86 side, but in the meantime I think we're getting close enough to start discussing the mm code. So.. does anyone have a bit of time to look over this and see if the implementation makes sense? Is the basic idea on the right lines? Also if there's anything I can do to make that easier (is it worth rebasing?) let me know. Also, I guess I should also note my aspirational plan for the next few months, it goes... 1. Get a convincing PoC working that improves the FIO degradation. 2. Gather it into a fairly messy but at least surveyable branch and push that to Github or whatever. 3. Show that to x86 folks and hopefully (!!) get some maintainers to give a nod like "yep we want ASI and we're more or less sold that the developers know how to make it performant". 4. Turn this [RFC] into a [PATCH]. So start by trying to merge the stuff that manages the restricted address space, leaving the logic of actually _using_ it for a later series. 5. [Maybe this can be partially paralellised with 4] start a new [PATCH] series that starts adding in the x86 stuff to actually switch address spaces etc. Basically this means respinning the patches that Boris has reviewed in [1]. Since we already have the page_alloc stuff, it should be possible to start testing this code end-to-end quickly. [1] https://lore.kernel.org/linux-mm/20250110-asi-rfc-v2-v2-0-8419288bc805@google.com/ Anyone have any thoughts on that overall strategy? Cheers, Brendan