From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4608F3C73F7; Thu, 30 Jul 2026 12:39:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785415199; cv=none; b=VK4tSoWw7Egc4RiMRRFxMd4zvdi34P6Ldkyt0De7ZM7goy6yw5+ggOeOhM5zEHDonhqP7Mtlw1d6A1aDl4VYX0RnXBRe1SRhZLs/TawycaZqLDTixygEWTLtui/mJC0o1DjuYFVJiJ+L1SOu07VanvzesFVC4zjYL4KoOHBD22A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785415199; c=relaxed/simple; bh=+DOGoQo9Jue42lb1rwBSLX9vhDY9ntgxYJroTDsXlHs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=AEEgqb3m3LegVhdTu4risv5leX0ZzKC6qyO1F7+x82HyvwGN+u+u5nR+qNO6wS81P8bTJ4NUvOWYaRRjASC2Qc2IzyfdM5LAkcS8FVJTVLLGIIP4Lxdda7i9Ul/W24ftI/C4LKaWute/UFIe8nJyXjUP2TG7b6fHg+dUYOYMeWo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JjGo0+ef; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JjGo0+ef" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CBADA1F00A3D; Thu, 30 Jul 2026 12:39:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785415198; bh=EWd1k8EXIqwmRQHt1JMH5oDb5WZp1Mtdat7Fpqf7Ea8=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=JjGo0+ef6V7aGBLPT5F6flIjmLAIVBu7nXTqOXTO5IewpJ5zjLsOqQ/jeDmpRppDP Ck1UcyOGvG5OFSJ0FyGlNR/jiDcssR0+7uWYI1i+j0CU4dtCu0z/ZOwtsLuhShuBPz yHCpJdgyzBbx0nsAc9QgZW87nAn1jEDg4d/Wo42hDqUWr8+yvtCMPhULD3+BZG2Oie ElkNXvxNs1I0BZm67/yZwDr7Rv6ti/MAblPee+0lf8KbmIWxBhEflKuFxSrqB37l82 CGA/kgO5cW6hAsk5dTLTrXHeqwIRcuk8btez7hGCF8WntkdR0BjjvUF/QjOtdBdPSd AXWHuBGrqqRfw== Message-ID: <1acb7ba0-6aff-4d30-9554-283ac8fbc93f@kernel.org> Date: Thu, 30 Jul 2026 14:39:51 +0200 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm/page_reporting: Add page_reporting_delay_ms module parameter To: "Lorenzo Stoakes (ARM)" , Pratyush Mallick Cc: akpm@linux-foundation.org, vbabka@kernel.org, sj@kernel.org, corbet@lwn.net, skhan@linuxfoundation.org, anshuman.khandual@arm.com, gthelen@google.com, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, liam@infradead.org, rppt@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org References: <20260727230545.262579-1-pratmal@google.com> <91b61f02-c533-41b9-b680-7de52a5c6918@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit >>> With 2s, we wait 2s before we start reporting immediately by kicking the >>> workqueue immediately. >>> >>> So "0" does not mean "report all the time", rather "start reporting immediately >>> as we are notified about a pageblock to report". > > No, it's whenever pageblock_order is specified, defaulting to a pageblock. > > But I guess in practice fine. > > There's fun like this in virtio_balloon.c btw: > > /* > * The default page reporting order is @pageblock_order, which > * corresponds to 512MB in size on ARM64 when 64KB base page > * size is used. The page reporting won't be triggered if the > * freeing page can't come up with a free area like that huge. > * So we specify the page reporting order to 5, corresponding > * to 2MB. It helps to avoid THP splitting if 4KB base page > * size is used by host. > * > * Ideally, the page reporting order is selected based on the > * host's base page size. However, it needs more work to report > * that value. The hard-coded order would be fine currently. > */ > #if defined(CONFIG_ARM64) && defined(CONFIG_ARM64_64K_PAGES) > vb->pr_dev_info.order = 5; > #endif Yes, it's really about "a large chunk of memory was freed". On 64k " a large chunk" is unfortunately order 5 == 2MiB (so the same as on 4k where a pageblock is 2M). -- Cheers, David