From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v2 0/7] mm: pages for hugetlb's overcommit may be able to charge to memcg To: Punit Agrawal Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , Jonathan Corbet , "Luis R. Rodriguez" , Kees Cook , Andrew Morton , Roman Gushchin , David Rientjes , Mike Kravetz , "Aneesh Kumar K.V" , Naoya Horiguchi , Anshuman Khandual , Marc-Andre Lureau , Dan Williams , Vlastimil Babka , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org References: <871se5ysbg.fsf@e105922-lin.cambridge.arm.com> From: TSUKADA Koutaro Message-ID: <9456064b-3ae1-0234-a1fc-918708156b6a@ascade.co.jp> Date: Tue, 22 May 2018 21:56:42 +0900 MIME-Version: 1.0 In-Reply-To: <871se5ysbg.fsf@e105922-lin.cambridge.arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: Hi Punit, On 2018/05/21 23:52, Punit Agrawal wrote: > Hi Tsukada, > > I was staring at memcg code to better understand your changes and had > the below thought. > > TSUKADA Koutaro writes: > > [...] > >> In this patch-set, introduce the charge_surplus_huge_pages(boolean) to >> struct hstate. If it is true, it charges to the memory cgroup to which the >> task that obtained surplus hugepages belongs. If it is false, do nothing as >> before, and the default value is false. The charge_surplus_huge_pages can >> be controlled procfs or sysfs interfaces. > > Instead of tying the surplus huge page charging control per-hstate, > could the control be made per-memcg? > > This can be done by introducing a per-memory controller file in sysfs > (memory.charge_surplus_hugepages?) that indicates whether surplus > hugepages are to be charged to the controller and forms part of the > total limit. IIUC, the limit already accounts for page and swap cache > pages. > > This would allow the control to be enabled per-cgroup and also keep the > userspace control interface in one place. > > As said earlier, I'm not familiar with memcg so the above might not be a > feasible but think it'll lead to a more coherent user > interface. Hopefully, more knowledgeable folks on the thread can chime > in. > Thank you for good advise. As you mentioned, it is better to be able to control by per-memcg. After organizing my thoughts, I will develop the next version patch-set that can solve issues and challenge again. Thanks, Tsukada > Thanks, > Punit > >> Since THP is very effective in environments with kernel page size of 4KB, >> such as x86, there is no reason to positively use HugeTLBfs, so I think >> that there is no situation to enable charge_surplus_huge_pages. However, in >> some distributions such as arm64, the page size of the kernel is 64KB, and >> the size of THP is too huge as 512MB, making it difficult to use. HugeTLBfs >> may support multiple huge page sizes, and in such a special environment >> there is a desire to use HugeTLBfs. >> >> The patch set is for 4.17.0-rc3+. I don't know whether patch-set are >> acceptable or not, so I just done a simple test. >> >> Thanks, >> Tsukada >> >> TSUKADA Koutaro (7): >> hugetlb: introduce charge_surplus_huge_pages to struct hstate >> hugetlb: supports migrate charging for surplus hugepages >> memcg: use compound_order rather than hpage_nr_pages >> mm, sysctl: make charging surplus hugepages controllable >> hugetlb: add charge_surplus_hugepages attribute >> Documentation, hugetlb: describe about charge_surplus_hugepages >> memcg: supports movement of surplus hugepages statistics >> >> Documentation/vm/hugetlbpage.txt | 6 + >> include/linux/hugetlb.h | 4 + >> kernel/sysctl.c | 7 + >> mm/hugetlb.c | 148 +++++++++++++++++++++++++++++++++++++++ >> mm/memcontrol.c | 109 +++++++++++++++++++++++++++- >> 5 files changed, 269 insertions(+), 5 deletions(-)