From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 1A14D1607AD for ; Wed, 24 Apr 2024 15:34:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713972896; cv=none; b=B3mDeMbH6Ynyz2z7+v6nAs37o/AgoWRvCtOn2Yp/0ID0tZnv4m+VdJNXY3sdL6/b0oBW5rk/NQk5Ci6z2KoaDrtZuMh9XnjIkLDY82TpOG1ou87qDGKucsFBVTcS2WDKc5cji2z0D3FFNH6q+zuHEFCR/ZeTraMElb4xWGLKxnk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713972896; c=relaxed/simple; bh=TttsruVEiGpEdTihSdZHPGzRR4e3nj8xOXWaY9wj/K4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=L4YDUGLQ47iHYgOsjxabxlImW5JymFXT3Y/08/cUVAubPbTe9nAlLAHpaYrnrDADQV+MIpMptVXrY4eR4aEUeQgb+bhD88uhQKmTlWsIKgcKucR+L8s3x+Sz6JG6NVvjn1g/F6JSV/2MONQ8k8D4kereGeaCkC8Mn4drSJKQDd8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 329421063; Wed, 24 Apr 2024 08:35:19 -0700 (PDT) Received: from [10.1.25.156] (XHFQ2J9959.cambridge.arm.com [10.1.25.156]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7A55A3F73F; Wed, 24 Apr 2024 08:34:50 -0700 (PDT) Message-ID: <0534d647-0753-4c34-943c-e705db1fbddd@arm.com> Date: Wed, 24 Apr 2024 16:34:49 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] mm: add docs for per-order mTHP split counters Content-Language: en-GB To: Lance Yang , akpm@linux-foundation.org Cc: 21cnbao@gmail.com, david@redhat.com, baolin.wang@linux.alibaba.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20240424135148.30422-1-ioworker0@gmail.com> <20240424135148.30422-3-ioworker0@gmail.com> From: Ryan Roberts In-Reply-To: <20240424135148.30422-3-ioworker0@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 24/04/2024 14:51, Lance Yang wrote: > This commit introduces documentation for mTHP split counters in > transhuge.rst. > > Signed-off-by: Lance Yang > --- > Documentation/admin-guide/mm/transhuge.rst | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst > index f82300b9193f..35d574a531c8 100644 > --- a/Documentation/admin-guide/mm/transhuge.rst > +++ b/Documentation/admin-guide/mm/transhuge.rst > @@ -475,6 +475,22 @@ anon_swpout_fallback > Usually because failed to allocate some continuous swap space > for the huge page. > > +split_page > + is incremented every time a huge page is split into base perhaps "...successfully split into base..." to make it clear that this is only incremented on success. > + pages. This can happen for a variety of reasons but a common > + reason is that a huge page is old and is being reclaimed. > + This action implies splitting all PMD/PTE mapped with the huge page. What does it mean to "split all PTE"? It's already at its smallest granularity. Perhaps "This action implies splitting any block mappings into PTEs."? > + > +split_page_failed > + is incremented if kernel fails to split huge > + page. This can happen if the page was pinned by somebody. > + > +deferred_split_page > + is incremented when a huge page is put onto split > + queue. This happens when a huge page is partially unmapped and > + splitting it would free up some memory. Pages on split queue are > + going to be split under memory pressure. > + > As the system ages, allocating huge pages may be expensive as the > system uses memory compaction to copy data around memory to free a > huge page for use. There are some counters in ``/proc/vmstat`` to help