Messages in this thread | | | Subject | Re: [PATCH] mm: Free per cpu pages async to shorten program exit time | From | David Hildenbrand <> | Date | Mon, 11 Oct 2021 11:40:12 +0200 |
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On 11.10.21 11:28, Michal Hocko wrote: > On Fri 08-10-21 10:17:50, David Hildenbrand wrote: >> On 08.10.21 08:39, ultrachin@163.com wrote: >>> From: chen xiaoguang <xiaoggchen@tencent.com> >>> >>> The exit time is long when program allocated big memory and >>> the most time consuming part is free memory which takes 99.9% >>> of the total exit time. By using async free we can save 25% of >>> exit time. >>> >>> Signed-off-by: chen xiaoguang <xiaoggchen@tencent.com> >>> Signed-off-by: zeng jingxiang <linuszeng@tencent.com> >>> Signed-off-by: lu yihui <yihuilu@tencent.com> >> >> I recently discussed with Claudio if it would be possible to tear down the >> process MM deferred, because for some use cases (secure/encrypted >> virtualization, very large mmaps) tearing down the page tables is already >> the much more expensive operation. >> >> There is mmdrop_async(), and I wondered if one could reuse that concept when >> tearing down a process -- I didn't look into feasibility, however, so it's >> just some very rough idea. > > This is not a new problem. Large process tear down can take ages. The > primary road block has been accounting. This lot of work has to be > accounted to the proper domain (e.g. cpu cgroup).
In general, yes. For some setups where admins don't care about that accounting (e.g., enabled via some magic toggle for large VMs), I guess this accounting isn't the major roadblock, correct?
-- Thanks,
David / dhildenb
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