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[31.46.243.128]) by smtp.gmail.com with ESMTPSA id p1-20020a05600c204100b003d99a39b846sm65434wmg.5.2023.01.05.19.12.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Jan 2023 19:12:51 -0800 (PST) Sender: Ingo Molnar Date: Fri, 6 Jan 2023 04:12:49 +0100 From: Ingo Molnar To: Aaron Thompson Cc: Mike Rapoport , linux-mm@kvack.org, "H. Peter Anvin" , Alexander Potapenko , Andrew Morton , Andy Shevchenko , Ard Biesheuvel , Borislav Petkov , Darren Hart , Dave Hansen , David Rientjes , Dmitry Vyukov , Ingo Molnar , Marco Elver , Thomas Gleixner , kasan-dev@googlegroups.com, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v2 1/1] mm: Always release pages to the buddy allocator in memblock_free_late(). Message-ID: References: <010101857bbc3a41-173240b3-9064-42ef-93f3-482081126ec2-000000@us-west-2.amazonses.com> <20230105041650.1485-1-dev@aaront.org> <010001858025fc22-e619988e-c0a5-4545-bd93-783890b9ad14-000000@email.amazonses.com> <0101018584d0b5a3-ea0e4d67-b00f-4254-8e1c-767fcafbec31-000000@us-west-2.amazonses.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0101018584d0b5a3-ea0e4d67-b00f-4254-8e1c-767fcafbec31-000000@us-west-2.amazonses.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Aaron Thompson wrote: > > On 2023-01-05 02:48, Ingo Molnar wrote: > > * Aaron Thompson wrote: > > > > > For example, on an Amazon EC2 t3.micro VM (1 GB) booting via EFI: > > > > > > v6.2-rc2: > > > # grep -E 'Node|spanned|present|managed' /proc/zoneinfo > > > Node 0, zone DMA > > > spanned 4095 > > > present 3999 > > > managed 3840 > > > Node 0, zone DMA32 > > > spanned 246652 > > > present 245868 > > > managed 178867 > > > > > > v6.2-rc2 + patch: > > > # grep -E 'Node|spanned|present|managed' /proc/zoneinfo > > > Node 0, zone DMA > > > spanned 4095 > > > present 3999 > > > managed 3840 > > > Node 0, zone DMA32 > > > spanned 246652 > > > present 245868 > > > managed 222816 # +43,949 pages > > > > [ Note the annotation I added to the output - might be useful in the > > changelog too. ] > > > > So this patch adds around +17% of RAM to this 1 GB virtual system? That > > looks rather significant ... > > > > Thanks, > > > > Ingo > > It is significant, but I wouldn't describe it as being added. I would say > that the system is currently losing 17% of RAM due to a bug, and this patch > fixes that bug. To the end-user gaining +17% [or +3%] extra usable RAM compared to what they had before is what matters, and it's a big deal. :-) Thanks, Ingo