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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1F847C5AD49 for ; Thu, 29 May 2025 18:14:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B61486B0089; Thu, 29 May 2025 14:14:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B39506B008C; Thu, 29 May 2025 14:14:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A76EE6B0092; Thu, 29 May 2025 14:14:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 88ABD6B0089 for ; Thu, 29 May 2025 14:14:09 -0400 (EDT) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id F357C120F15 for ; Thu, 29 May 2025 18:14:08 +0000 (UTC) X-FDA: 83496744576.05.C4138A8 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf26.hostedemail.com (Postfix) with ESMTP id B1B10140018 for ; Thu, 29 May 2025 18:14:06 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=A4O80ONX; spf=none (imf26.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1748542447; 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=JsHVVGE7ieSHfCbQBVFyFeTA0LwLqupquZVk14tO7oA=; b=68apyEOY8fQHj+cMG1G/IiHvmHNUR35K7poZXJZ2FgpxgIWSBZViSEp0fbX/5uCWYpFB7e Qs7y0VqOvCHwsED/jL24UrGYukuACumgGSHbwBV3PDzlsO6697CAs+DvViIwZVH5YzvNiZ zszwgcleW3u/fb1JBGnYDF9+7K6fQhw= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1748542447; a=rsa-sha256; cv=none; b=qgRYS9nCF0FDupvS5ZB+wyOec3ZAFCOpCiQjnHwoyz3J45yHxfH6oKz+xHX6OHJTf4MCU4 yWcDkzV4BfcjpJ/9J4Q2Ht8q95/jrqy15WHTAAK5W8EjPdRe1hgG1Lzy0FWB9/peHJ+IS2 OfQ8YV7Hzcc+hhHVizc2mByfVob5538= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=A4O80ONX; spf=none (imf26.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=JsHVVGE7ieSHfCbQBVFyFeTA0LwLqupquZVk14tO7oA=; b=A4O80ONX6IHwk3u4GHiU4vvuRp l74f6fcZygTPkGEitrjnrrS1bZlJ/L7suMys+yaEDzTZ9MHINyOmfMRGAMwXtlGzgECZMEUH+2rGd pz3o8QwO38kr5QQmKrD23Ec83ZQEBQ6DhD315iQZoLqAohU8XaL8ary0zSgeVs/txpFflKzWQsayL kQlnSWT99/SM8WoKyNmFQwn+TGivm6T8r1kWBj5tF78uGkmoltkyDYeFhqdC4LZ7Tq2FP+CP2tTn6 16AHInBnbO6vT5bOJZoPChoZs0IMncGgoLdoJWQ8J6wM+EtoYULvfoxosK/vBxm9bD/zS4vixdBr7 zTWX7t5A==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uKhlO-0000000F03Z-04m6; Thu, 29 May 2025 18:13:58 +0000 Date: Thu, 29 May 2025 19:13:57 +0100 From: Matthew Wilcox To: Shakeel Butt Cc: Lorenzo Stoakes , Andrew Morton , "Liam R . Howlett" , David Hildenbrand , Vlastimil Babka , Jann Horn , Arnd Bergmann , Christian Brauner , SeongJae Park , Usama Arif , Mike Rapoport , Johannes Weiner , Barry Song <21cnbao@gmail.com>, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Pedro Falcato Subject: Re: [DISCUSSION] proposed mctl() API Message-ID: References: <85778a76-7dc8-4ea8-8827-acb45f74ee05@lucifer.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: B1B10140018 X-Stat-Signature: gm6ie89uxrbzhexpdjpbboz373e4pa6a X-Rspam-User: X-HE-Tag: 1748542446-223541 X-HE-Meta: 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 zRPpKaw/ f12kwExVdBHfaF4MwVR16UxZ1rb9RubQuWajDLoCbzz6Rzo4jooFq6DnGdYcNra5X9PPI5LPkfaLJGE3sK8dKwwQQV1kvg5rHdxPWh174jxpGhc7nejFL4002j+06ZH8Havekkf1ZEy+b0V4+4LBPlcQRNBawi4d1nDRwbpiY/LcOv+ZS6fXooSeeJckDUzGvPnsao4Ko8Y4ewBgoLgPFSQOYeFizZDAu3Z8wW5TNn61Gulw= 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 Thu, May 29, 2025 at 10:54:34AM -0700, Shakeel Butt wrote: > On Thu, May 29, 2025 at 04:28:46PM +0100, Matthew Wilcox wrote: > > People should put more effort into allocating THPs automatically and > > monitoring where they're helping performance and where they're hurting > > performance, > > Can you please expand on people putting more effort? Is it about > workloads or maybe malloc implementations (tcmalloc, jemalloc) being > more intelligent in managing their allocations/frees to keep more used > memory in hugepage aligned regions? And conveying to kernel which > regions they prefer hugepage backed and which they do not? Or something > else? We need infrastructure inside the kernel to monitor whether a task is making effective use of the THPs that it has, and if it's not then move those THPs over to where they will be better used. I don't necessarily object to userspace giving hints like "I think I'm going to use all of this 20MB region quite heavily", but the kernel should treat those hints with the appropriate skepticism, otherwise it's just a turbo button that nobody would ever _not_ press. > > instead of coming up with these baroque reasons to blame > > the sysadmin for not having tweaked some magic knob. > > To me this is not about blaming sysadmin but more about sysadmin wanting > more fine grained control on THP allocation policies for different > workloads running in a multi-tenant environment. That's the same thing. Linux should be auto-tuning, not relying on some omniscient sysadmin to fix it up.