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 3A60844369 for ; Fri, 12 Apr 2024 10:19:59 +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=1712917201; cv=none; b=SoIcF/LtDJTicJVMRk8x8/2LctUNeSTi9KfxzjrHnMdEvFA3lV/r3X76VE7sJNYh9hkvsvXQ4FAZrNy7BHpGPHajDhUi5d9n2nEydSyM1tcIpFzhif0EudgZdR2KV5qiN6v+vxGfzxQXk6bpqT6uGFJKWi+fw7JclHM72sHKIx8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712917201; c=relaxed/simple; bh=K9W+Y4I98n2qqn8cSmOOvctrkBrlVZxDqpqIIWfNgRA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=rW/GXMg9Hw9TgkbLMajQOy3PpKQGzo2H4KFGMcLbd5sBFLYMJLgYQhBlIqo20kHejqnt2LxLp6+XxvTNcMdqQawTUEb+usWxToH2xPyM/kvwqQLfo9VEMTx146arL2a1UvMcqmWe958AB00qqX+Jr5CkbnVMqz842U4VH4OuE34= 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 C11CD339; Fri, 12 Apr 2024 03:20:28 -0700 (PDT) Received: from [10.57.73.208] (unknown [10.57.73.208]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 82D393F64C; Fri, 12 Apr 2024 03:19:57 -0700 (PDT) Message-ID: Date: Fri, 12 Apr 2024 11:19:56 +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 v5 3/4] mm: add docs for per-order mTHP counters and transhuge_page ABI Content-Language: en-GB To: Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org Cc: cerasuolodomenico@gmail.com, chrisl@kernel.org, david@redhat.com, kasong@tencent.com, linux-kernel@vger.kernel.org, peterx@redhat.com, surenb@google.com, v-songbaohua@oppo.com, willy@infradead.org, yosryahmed@google.com, yuzhao@google.com, corbet@lwn.net References: <20240412073740.294272-1-21cnbao@gmail.com> <20240412073740.294272-4-21cnbao@gmail.com> From: Ryan Roberts In-Reply-To: <20240412073740.294272-4-21cnbao@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 12/04/2024 08:37, Barry Song wrote: > From: Barry Song > > This patch includes documentation for mTHP counters and an ABI file > for sys-kernel-mm-transparent-hugepage, which appears to have been > missing for some time. > > Signed-off-by: Barry Song > Cc: Chris Li > Cc: David Hildenbrand > Cc: Domenico Cerasuolo > Cc: Kairui Song > Cc: Matthew Wilcox (Oracle) > Cc: Peter Xu > Cc: Ryan Roberts > Cc: Suren Baghdasaryan > Cc: Yosry Ahmed > Cc: Yu Zhao > Cc: Jonathan Corbet A few nits, but regardless: Reviewed-by: Ryan Roberts > --- > .../sys-kernel-mm-transparent-hugepage | 17 +++++++++++ > Documentation/admin-guide/mm/transhuge.rst | 28 +++++++++++++++++++ > 2 files changed, 45 insertions(+) > create mode 100644 Documentation/ABI/testing/sys-kernel-mm-transparent-hugepage > > diff --git a/Documentation/ABI/testing/sys-kernel-mm-transparent-hugepage b/Documentation/ABI/testing/sys-kernel-mm-transparent-hugepage > new file mode 100644 > index 000000000000..80dde0fd576c > --- /dev/null > +++ b/Documentation/ABI/testing/sys-kernel-mm-transparent-hugepage > @@ -0,0 +1,17 @@ > +What: /sys/kernel/mm/hugepages/ Err, transparent_hugepage, right? copy/paste error? > +Date: April 2024 > +Contact: Barry Song Looks like a bunch of mm sysfs interfaces use: Contact: Linux memory management mailing list I'll leave that up to you! > +Description: > + /sys/kernel/mm/transparent_hugepage/ contains a number of files and > + subdirectories, > + - defrag > + - enabled > + - hpage_pmd_size > + - khugepaged > + - shmem_enabled > + - use_zero_page > + - subdirectories of the form hugepages-kB, where > + is the page size of the hugepages supported by the kernel/CPU > + combination. > + > + See Documentation/admin-guide/mm/transhuge.rst for details.> diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst > index 04eb45a2f940..f436ff982f22 100644 > --- a/Documentation/admin-guide/mm/transhuge.rst > +++ b/Documentation/admin-guide/mm/transhuge.rst > @@ -447,6 +447,34 @@ thp_swpout_fallback > Usually because failed to allocate some continuous swap space > for the huge page. > > +In /sys/kernel/mm/transparent_hugepage/hugepages-kB/stats, There are > +also individual counters for each huge page size, which can be utilized to > +monitor the system's effectiveness in providing huge pages for usage. Each > +counter has its own corresponding file. > + > +anon_fault_alloc > + is incremented every time a huge page is successfully > + allocated and charged to handle a page fault. > + > +anon_fault_fallback > + is incremented if a page fault fails to allocate or charge > + a huge page and instead falls back to using huge pages with > + lower orders or small pages. > + > +anon_fault_fallback_charge > + is incremented if a page fault fails to charge a huge page and > + instead falls back to using huge pages with lower orders or > + small pages even though the allocation was successful. > + > +anon_swpout > + is incremented every time a huge page is swapout in one nit: swapout -> "swapped out"? Although I see this is just a copy/paste of the description of the existing counter... > + piece without splitting. > + > +anon_swpout_fallback > + is incremented if a huge page has to be split before swapout. > + Usually because failed to allocate some continuous swap space > + for the huge page. > + > 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