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b=umsUWZmOqvANgNUoTnjagOzV0EHGA3V3Jc0kOhqq3BacTVLKB4T5iuF2crzGzGHoX /HNogFnHSSVCddBypl0jo8EYaUyMSeY2+EhLBscXZ4/+QEP501cZWNOWJzFoIkBs8g M3Oafg/8XM13jbaIqwfJEOKbbXi1O5LWT6xlsfBE= Date: Sun, 16 Mar 2025 18:02:50 -0700 From: Andrew Morton To: Michal Clapinski Cc: Vlastimil Babka , Pasha Tatashin , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 0/2] mm/compaction: allow more aggressive proactive compaction Message-Id: <20250316180250.70767a305cea9798dcc7c9b8@linux-foundation.org> In-Reply-To: <20250127215020.4023545-1-mclapinski@google.com> References: <20250127215020.4023545-1-mclapinski@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: d58w7pksfr8wn1g51fgyjpf6dtkrcuny X-Rspamd-Queue-Id: 1C7158000B X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1742173371-278169 X-HE-Meta: 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 NO8amK7L qvKWzl9XuiYpfTQ1XEnXZxIUvee8L+cZj5gqqWHiB6M3TZuugEeBKKJ2QZf2ojxnAD9rsCI/C1t6H89yvsoOXDnAaPh2Shd5Fjn9fq8rQLMBIsn3ghEBgE4/7zO8SRYHQMWBqjOH3P9rJH21ZwwVE3zjCoqmhFcMM5rqH+NQte3e3QjY49aLsg16AwQbY1bVmH+ZeU6ymrsbt8QTtf5O5t6445l76Ug2PyC0Tlm2cWjrRW/bFNli0zf4rKIqAV1yIUx1Au/ydJzGzhPc= 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 Mon, 27 Jan 2025 22:50:18 +0100 Michal Clapinski wrote: > Our goal is to keep memory usage of a VM low on the host. For that > reason, we use free page reporting which by default reports free pages > of order 9 and larger to the host to be freed. The feature works well > only if the memory in the guest is not fragmented below pages of order > 9. Proactive compaction can be reused to achieve defragmentation after > some parameter tweaking. > > When the fragmentation score (lower is better) gets larger than the > high watermark, proactive compaction kicks in. Compaction stops when > the score goes below the low watermark (or no progress is made and > backoff kicks in). Let's define the difference between high and low > watermarks as leeway. Before these changes, the minimum possible value > for low watermark was 5 and the leeway was hardcoded to 10 (so minimum > possible value for high watermark was 15). > I'm not seeing enthusiasm for these changes and a couple of comments from myself remain unaddressed. I'll drop the series - let's revisit in the next -rc cycle, if you feel so motivated.