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Thu, 13 Oct 2022 16:13:59 -0400 (EDT) References: <20221011010044.851537-1-shr@devkernel.io> User-agent: mu4e 1.6.11; emacs 28.1.91 From: Stefan Roesch To: Matthew Wilcox Cc: kernel-team@fb.com, linux-block@vger.kernel.org, linux-mm@kvack.org, axboe@kernel.dk, clm@meta.com Subject: Re: [RFC PATCH v1 00/14] mm/block: add bdi sysfs knobs Date: Thu, 13 Oct 2022 13:11:22 -0700 In-reply-to: Message-ID: MIME-Version: 1.0 Content-Type: text/plain ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=devkernel.io header.s=fm1 header.b="tgF/BVNW"; dkim=pass header.d=messagingengine.com header.s=i84614614.fm3 header.b="s/sAGUJv"; spf=pass (imf18.hostedemail.com: domain of shr@devkernel.io designates 64.147.123.18 as permitted sender) smtp.mailfrom=shr@devkernel.io; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665692043; a=rsa-sha256; cv=none; b=VjquAY9QriOoBJ43xtSmQiFe3bzqN4AeA2xNWj4Ax2ORVx21ybfS5k8b0mxfDc7ekzRrj6 pMbKG5G0Ch79sVYrHguMRNHqZbK0/+h0zM2Nbeb6gzV91tYKP+5nwHUOll4ASWEYx8RO9J i2aGy/cfrrhRAzGmQnYeWGRR1mLdn70= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665692043; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=l2inNZMIPId3zeZXqLQOmIFTkdONrtoZr3dSGGxvchw=; b=df7YJXZKDimLuZUGUTPs5TQh0RLKZnWI69xebcfqygQYuwNSPBPJxCMO0y9KURbmzB4XYi MveKphr3h8Jtd9l6cP00IGe7atOubNxqn37AxWc/3riQ+7BsnSHZpiewV808dN7R7zglVk tT4naqD2WA6X7nbXV1XkxpuxZC98ZTw= X-Rspamd-Queue-Id: E49C31C0030 X-Rspam-User: Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=devkernel.io header.s=fm1 header.b="tgF/BVNW"; dkim=pass header.d=messagingengine.com header.s=i84614614.fm3 header.b="s/sAGUJv"; spf=pass (imf18.hostedemail.com: domain of shr@devkernel.io designates 64.147.123.18 as permitted sender) smtp.mailfrom=shr@devkernel.io; dmarc=none X-Rspamd-Server: rspam04 X-Stat-Signature: jc6muwzdmtu8eaoji6gm84cfeta5zitk X-HE-Tag: 1665692042-869880 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Matthew Wilcox writes: > On Mon, Oct 10, 2022 at 06:00:30PM -0700, Stefan Roesch wrote: >> 2) Part of 10000 internal calculation >> The max_ratio is based on percentage. With the current machine sizes percentage >> values can be very high (1% of a 256GB main memory is already 2.5GB). This change >> uses part of 10000 instead of percentages for the internal calculations. > > Why 10,000? If you need better accuracy than 1/1000, the next step > should normally be parts per million. For current main memory sizes 1000 is enough. I wanted to give some additional headroom. Parts per million is too much. In the next version of the patch, I'll change it to parts per 1000.