From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A488EC433EF for ; Wed, 27 Oct 2021 17:12:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2CF0860F56 for ; Wed, 27 Oct 2021 17:12:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2CF0860F56 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 26BC1940007; Wed, 27 Oct 2021 13:12:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1F3C06B0072; Wed, 27 Oct 2021 13:12:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 09640940007; Wed, 27 Oct 2021 13:12:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0188.hostedemail.com [216.40.44.188]) by kanga.kvack.org (Postfix) with ESMTP id D28F06B0071 for ; Wed, 27 Oct 2021 13:12:55 -0400 (EDT) Received: from smtpin38.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 627EF39F36 for ; Wed, 27 Oct 2021 17:12:55 +0000 (UTC) X-FDA: 78742862310.38.DC5F4FF Received: from mail-ed1-f50.google.com (mail-ed1-f50.google.com [209.85.208.50]) by imf21.hostedemail.com (Postfix) with ESMTP id DE05FD036A43 for ; Wed, 27 Oct 2021 17:12:51 +0000 (UTC) Received: by mail-ed1-f50.google.com with SMTP id z20so13514438edc.13 for ; Wed, 27 Oct 2021 10:12:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=tH7RXzLpAf1QKtyCApDcv6votoC2qVXcBbg2ND+EBLQ=; b=aT1X9fljr20Omg8rLQRjW4UI5dTJeyneVY3Q/XGVdIyxRHJn1mVbHHFy/mOusZXRmt nzWnBaLpiov0PeU+vRqMBgFRzh1anwqMLgftQVperQQvtemxil2hPXxyEpwcnPgsgIEV 1f/USevhcNwXYuUygYaNpWAjd5V3ru6RjDAc+/WFn6X4gfIdCo3954lyB6ZskatpRHC+ 8UHaKBl38MT37kPCKNybgb0b4gDlUvQVCzMNJP9OFOXXc6KY8GH5pxP42UuM4nYbYE7N za2i/1oaSNZZ2TkpeuorswzYZMD9eU9yu2dbbkx79+sEBJIlJ5x/M4xFJXH9D1wGteYy q23A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=tH7RXzLpAf1QKtyCApDcv6votoC2qVXcBbg2ND+EBLQ=; b=5O0KKHfUrceKyApfacqV+Izg0eo1Aqecv1cjcQlm9wli/TXXq7hwOv+0Rc/zktfovh mzGV92F/jYRqVksecKwvWO4wGFhDP4ww7Q20m1sZnwOpcClvGGPi+ErDUSFrgVcActfU P0EFqT/405+4pqAxeXBptmZRPLwoWzhQhanWpx2nTevx07Lrq3hyLVWRVVHyzoSeRfKH hNiVy0MHcr067eaiSbTgfVhqfo2J18e84w2ATB1CUsHXzj+LFoWVLlm4RBOrN2Svc1MO UDEZcARxS+uDnWzaAWpPb2tkpq9iOj3xwvkVRsrMzvOmHuNlL9Uq8dHXNzwo8B5GryQQ zw+Q== X-Gm-Message-State: AOAM5339tUflsR35buLRkXtQKWmGwDG6+298JkZ7GdCHyVceWYkX7p6o QwPxBw2iBN+6qSTjUxwFvgjb4zNy3+5mJ/rJ0Dw= X-Google-Smtp-Source: ABdhPJzcfsCMDBF5nqQc2wnU3Zf56fvBRN0k+LlXkHcSBsM17xdto2qsahnl9fEwyiO5/NFSub1Aq5fdKiVRinG5h1M= X-Received: by 2002:a05:6402:10da:: with SMTP id p26mr46858447edu.283.1635354773755; Wed, 27 Oct 2021 10:12:53 -0700 (PDT) MIME-Version: 1.0 References: <71b597cb9a89c9f033861513da393501f04f4098.camel@infinera.com> In-Reply-To: <71b597cb9a89c9f033861513da393501f04f4098.camel@infinera.com> From: Yang Shi Date: Wed, 27 Oct 2021 10:12:41 -0700 Message-ID: Subject: Re: kernel 5.10.x Reserves much more RAM than 5.11.0, 8 MB vs 20 MB To: Joakim Tjernlund Cc: "linux-mm@kvack.org" Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: pm81z3i7g36srazoti73o1i9k3hjg9fb X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: DE05FD036A43 Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=aT1X9flj; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf21.hostedemail.com: domain of shy828301@gmail.com designates 209.85.208.50 as permitted sender) smtp.mailfrom=shy828301@gmail.com X-HE-Tag: 1635354771-744436 X-Bogosity: Ham, tests=bogofilter, spamicity=0.012535, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Oct 27, 2021 at 5:48 AM Joakim Tjernlund wrote: > > Using a fairly minimal kernel I get a big difference in Reserved memory, using: > qemu-system-aarch64 -machine virt -kernel arch/arm64/boot/Image -cpu cortex-a53 -nographic -m 32M > > I get this: > Linux version 5.11.0 > Memory: 24052K/32768K available (3520K kernel code, 684K rwdata, 548K rodata, 320K init, 245K bss, 8716K reserved, 0K cma-reserved) > > Versus: > > Linux version 5.10.75 > Memory: 11836K/32768K available (3518K kernel code, 684K rwdata, 540K rodata, 320K init, 244K bss, 20932K reserved, 0K cma-reserved) > > Reserving 20 MB RAM on a 32 MB is way too much, even 8Mb is a bit much for us. This might be caused by the new lockless printk buffer patch introduced in 5.10. We noticed this spike on 5.10 kernel too. It may have much more memory reserved for meta data and the total amount may be as much as 3x of log_buf_len. The amount varies on different platforms with different configs. I didn't dig too much into the details to figure out how it gets the number. You could try to adjust CONFIG_LOG_BUF_SHIFT or set log_buf_len from kernel commandline to limit the printk buffer size. > > Jocke > > PS. I hope this is the right list, please advise if it is not.