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Fri, 24 Nov 2023 11:24:29 -0800 (PST) Date: Fri, 24 Nov 2023 11:24:28 -0800 (PST) From: David Rientjes To: Charan Teja Kalla cc: akpm@linux-foundation.org, mgorman@techsingularity.net, mhocko@suse.com, david@redhat.com, vbabka@suse.cz, hannes@cmpxchg.org, quic_pkondeti@quicinc.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V3 2/2] mm: page_alloc: enforce minimum zone size to do high atomic reserves In-Reply-To: Message-ID: <01c81f6a-f090-a544-49db-ed9cd97ab8ee@google.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: 22DAB1C000C X-Rspam-User: X-Stat-Signature: fyrnmswgc45qmnb1ijbhj5o4sphztxxn X-Rspamd-Server: rspam03 X-HE-Tag: 1700853870-642939 X-HE-Meta: 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 vVcoKQC6 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.001994, 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 Fri, 24 Nov 2023, Charan Teja Kalla wrote: > Highatomic reserves are set to roughly 1% of zone for maximum and a > pageblock size for minimum. Encountered a system with the below > configuration: > Normal free:7728kB boost:0kB min:804kB low:1004kB high:1204kB > reserved_highatomic:8192KB managed:49224kB > > On such systems, even a single pageblock makes highatomic reserves are > set to ~8% of the zone memory. This high value can easily exert pressure > on the zone. > > Per discussion with Michal and Mel, it is not much useful to reserve > the memory for highatomic allocations on such small systems[1]. Since > the minimum size for high atomic reserves is always going to be a > pageblock size and if 1% of zone managed pages is going to be below > pageblock size, don't reserve memory for high atomic allocations. Thanks > Michal for this suggestion[2]. > > Since no memory is being reserved for high atomic allocations and if > respective allocation failures are seen, this patch can be reverted. > > [1] https://lore.kernel.org/linux-mm/20231117161956.d3yjdxhhm4rhl7h2@techsingularity.net/ > [2] https://lore.kernel.org/linux-mm/ZVYRJMUitykepLRy@tiehlicka/ > > Signed-off-by: Charan Teja Kalla Acked-by: David Rientjes