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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.63]); Tue, 24 Sep 2019 15:51:59 +0000 (UTC) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190924_085200_533048_AD63757B X-CRM114-Status: GOOD ( 18.61 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: yang.zhang.wz@gmail.com, pagupta@redhat.com, kvm@vger.kernel.org, mst@redhat.com, lcapitulino@redhat.com, linux-mm@kvack.org, alexander.h.duyck@linux.intel.com, aarcange@redhat.com, virtio-dev@lists.oasis-open.org, riel@surriel.com, willy@infradead.org, wei.w.wang@intel.com, vbabka@suse.cz, konrad.wilk@oracle.com, dan.j.williams@intel.com, linux-arm-kernel@lists.infradead.org, osalvador@suse.de, dave.hansen@intel.com, linux-kernel@vger.kernel.org, pbonzini@redhat.com, akpm@linux-foundation.org, mgorman@techsingularity.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 9/24/19 11:32 AM, David Hildenbrand wrote: > On 24.09.19 16:23, Michal Hocko wrote: >> On Wed 18-09-19 10:52:25, Alexander Duyck wrote: >> [...] >>> In order to try and keep the time needed to find a non-reported page to >>> a minimum we maintain a "reported_boundary" pointer. This pointer is used >>> by the get_unreported_pages iterator to determine at what point it should >>> resume searching for non-reported pages. In order to guarantee pages do >>> not get past the scan I have modified add_to_free_list_tail so that it >>> will not insert pages behind the reported_boundary. >>> >>> If another process needs to perform a massive manipulation of the free >>> list, such as compaction, it can either reset a given individual boundary >>> which will push the boundary back to the list_head, or it can clear the >>> bit indicating the zone is actively processing which will result in the >>> reporting process resetting all of the boundaries for a given zone. >> Is this any different from the previous version? The last review >> feedback (both from me and Mel) was that we are not happy to have an >> externally imposed constrains on how the page allocator is supposed to >> maintain its free lists. >> >> If this is really the only way to go forward then I would like to hear >> very convincing arguments about other approaches not being feasible. > Adding to what Alexander said, I don't consider the other approaches > (especially the bitmap-based approach Nitesh is currently working on) > infeasible. There might be more rough edges (e.g., sparse zones) and > eventually sometimes a little more work to be done, but definitely > feasible. Incorporating stuff into the buddy might make some tasks > (e.g., identify free pages) more efficient. My plan was to get a framework ready which can perform decently and is acceptable upstream (keeping core-mm changes to a minimum) and then keep optimizing it for different use-cases. Indeed, the bitmap-based approach may not be efficient for every available use case. But then I am not sure if we want to target that, considering it may require mm-changes. > I still somewhat like the idea of capturing hints of free pages (in > whatever data structure) and then going over the hints, seeing if the > pages are still free. Then only temporarily isolating the still-free > pages, reporting them, and un-isolating them after they were reported. I > like the idea that the pages are not fake-allocated but only temporarily > blocked. That works nicely e.g., with the movable zone (contain only > movable data). > > But anyhow, after decades of people working on free page > hinting/reporting, I am happy with anything that gets accepted upstream :D +1 > -- Nitesh _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel