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 <tsukada@xxxxxxxxxxxx> 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(-)
