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 4A0827D3E6 for ; Tue, 23 Apr 2024 11:39:58 +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=1713872400; cv=none; b=BP5BHnCO8XYOETdHmmoUNvqv4fEUYMDd6jjnYp+rL4j1/KK6byDrb4O4/zalkzd6M9X4H0ahnPPlkyCovZxPvdRQflpC/bMe6efwIR5MaM7ne6LybLXUoNi5xDuQqKrOzAw2kQ/Skt2filiez5FescGuT6tP7THrlOTXGklM9KU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713872400; c=relaxed/simple; bh=Po6RxZpb+2WLlQDdIGE/5n596gYUv/wQirH+33oGB18=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=PcQjSi/iZHss3X8HhjC9L4DqpxZpFU0NLsAs79U6uc1LG0/jDcUAPM4csV0etXhu2ttWHVc2dRXySFhiyOVYbjwoU/C335nlhxAkXHUdapm9XAe1wym+5L2FtpW/tjuoqc6rZ3COE1noj2zBOZwEct5IjRKfI6xewQzNS9Zz1Kc= 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 8A65C339; Tue, 23 Apr 2024 04:40:26 -0700 (PDT) Received: from [10.57.74.127] (unknown [10.57.74.127]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D1B7F3F7BD; Tue, 23 Apr 2024 04:39:56 -0700 (PDT) Message-ID: <5f147c9d-ba00-4757-b88e-38b45fffb8d3@arm.com> Date: Tue, 23 Apr 2024 12:39:55 +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: [RFC PATCH 5/5] mm: shmem: add anonymous share mTHP counters Content-Language: en-GB To: Baolin Wang , Barry Song <21cnbao@gmail.com> Cc: akpm@linux-foundation.org, hughd@google.com, willy@infradead.org, david@redhat.com, wangkefeng.wang@huawei.com, ying.huang@intel.com, shy828301@gmail.com, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <05d0096e4ec3e572d1d52d33a31a661321ac1551.1713755580.git.baolin.wang@linux.alibaba.com> <3045341d-06c2-4fdb-88a1-3f0d473f99ee@linux.alibaba.com> From: Ryan Roberts In-Reply-To: <3045341d-06c2-4fdb-88a1-3f0d473f99ee@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 23/04/2024 02:46, Baolin Wang wrote: > > > On 2024/4/23 09:17, Barry Song wrote: >> On Mon, Apr 22, 2024 at 3:03 PM Baolin Wang >> wrote: >>> >>> Signed-off-by: Baolin Wang >>> --- >>>   include/linux/huge_mm.h | 2 ++ >>>   mm/huge_memory.c        | 4 ++++ >>>   mm/shmem.c              | 5 ++++- >>>   3 files changed, 10 insertions(+), 1 deletion(-) >>> >>> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h >>> index 26b6fa98d8ac..67b9c1acad31 100644 >>> --- a/include/linux/huge_mm.h >>> +++ b/include/linux/huge_mm.h >>> @@ -270,6 +270,8 @@ enum mthp_stat_item { >>>          MTHP_STAT_ANON_SWPOUT, >>>          MTHP_STAT_ANON_SWPOUT_FALLBACK, >>>          MTHP_STAT_ANON_SWPIN_REFAULT, >>> +       MTHP_STAT_SHMEM_ANON_ALLOC, >>> +       MTHP_STAT_SHMEM_ANON_ALLOC_FALLBACK, >> >> not quite sure about this. for 2MB pmd-mapped THP shmem, we count them >> as FILE_THP. >> here we are counting as SHMEM_ANON. To me, SHMEM_ANON is more correct but >> it doesn't align with pmd-mapped THP. David, Ryan, what do you think? > > Thanks for reviewing. > > IMO, I think both approaches are acceptable, which also reflects the dual nature > of anonymous shared pages: on the one hand they are anonymous pages, and on the > other hand, they are backed by a pseudo file. From the user's perspective, I > prefer to use the term "anonymous shmem", which can be distinguished from the > real file-backed THP. > > Anyway, let's see what others think. >From a quick look at the code, it looks like the shmem alloc/fallback/charge events are all lumped in with FILE_THP. But the instantaneous "how many are allocated" and "how many are mapped" have their own NR_SHMEM_THPS and NR_SHMEM_PMDMAPPED counters? So its a bit inconsistent today. My preference would be to add these to be consistent with the anon stats: MTHP_STAT_SHMEM_FAULT_ALLOC, MTHP_STAT_SHMEM_FAULT_FALLBACK, MTHP_STAT_SHMEM_FAULT_FALLBACK_CHARGE, But it looks like these aren't always allocated due to faults? So perhaps: MTHP_STAT_SHMEM_ALLOC, MTHP_STAT_SHMEM_FALLBACK, MTHP_STAT_SHMEM_FALLBACK_CHARGE, If I've understood the code correctly (I know nothing about shmem), the allocation can be for both mmap(SHARED|ANON) and for tmpfs? So "SHMEM_ANON" probably isn't quite right? > >>>          __MTHP_STAT_COUNT >>>   }; >>> >>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >>> index 9e52c0db7580..dc15240c1ab3 100644 >>> --- a/mm/huge_memory.c >>> +++ b/mm/huge_memory.c >>> @@ -557,6 +557,8 @@ DEFINE_MTHP_STAT_ATTR(anon_alloc_fallback, >>> MTHP_STAT_ANON_ALLOC_FALLBACK); >>>   DEFINE_MTHP_STAT_ATTR(anon_swpout, MTHP_STAT_ANON_SWPOUT); >>>   DEFINE_MTHP_STAT_ATTR(anon_swpout_fallback, MTHP_STAT_ANON_SWPOUT_FALLBACK); >>>   DEFINE_MTHP_STAT_ATTR(anon_swpin_refault, MTHP_STAT_ANON_SWPIN_REFAULT); >>> +DEFINE_MTHP_STAT_ATTR(shmem_anon_alloc, MTHP_STAT_SHMEM_ANON_ALLOC); >>> +DEFINE_MTHP_STAT_ATTR(shmem_anon_alloc_fallback, >>> MTHP_STAT_SHMEM_ANON_ALLOC_FALLBACK); >>> >>>   static struct attribute *stats_attrs[] = { >>>          &anon_alloc_attr.attr, >>> @@ -564,6 +566,8 @@ static struct attribute *stats_attrs[] = { >>>          &anon_swpout_attr.attr, >>>          &anon_swpout_fallback_attr.attr, >>>          &anon_swpin_refault_attr.attr, >>> +       &shmem_anon_alloc_attr.attr, >>> +       &shmem_anon_alloc_fallback_attr.attr, >>>          NULL, >>>   }; >>> >>> diff --git a/mm/shmem.c b/mm/shmem.c >>> index 8b009e7040b2..4a0aa75ab29c 100644 >>> --- a/mm/shmem.c >>> +++ b/mm/shmem.c >>> @@ -1706,11 +1706,14 @@ static struct folio *shmem_alloc_and_add_folio(struct >>> vm_fault *vmf, >>>                          pages = 1 << order; >>>                          index = round_down(index, pages); >>>                          folio = shmem_alloc_hugefolio(gfp, info, index, order); >>> -                       if (folio) >>> +                       if (folio) { >>> +                               count_mthp_stat(order, >>> MTHP_STAT_SHMEM_ANON_ALLOC); is there any reason why this can't go next to the existing PMD-size stat? >>>                                  goto allocated; >>> +                       } >>> >>>                          if (pages == HPAGE_PMD_NR) >>>                                  count_vm_event(THP_FILE_FALLBACK); >>> +                       count_mthp_stat(order, >>> MTHP_STAT_SHMEM_ANON_ALLOC_FALLBACK); >>>                          order = next_order(&orders, order); >>>                  } >>>          } else { >>> -- >>> 2.39.3 >>> >> >> Thanks >> Barry