Messages in this thread | | | Subject | Re: [Phishing Risk] [External] Re: [PATCH 2/3] cgroup/cpuset: introduce cpuset.mems.migration | From | Abel Wu <> | Date | Wed, 5 May 2021 13:06:09 +0800 |
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ping :)
On 4/27/21 10:43 PM, Tejun Heo wrote: > Hello, > > On Mon, Apr 26, 2021 at 02:59:45PM +0800, Abel Wu wrote: >> When a NUMA node is assigned to numa-service, the workload >> on that node needs to be moved away fast and complete. The >> main aspects we cared about on the eviction are as follows: >> >> a) it should complete soon enough so that numa-services >> won’t wait too long to hurt user experience >> b) the workloads to be evicted could have massive usage on >> memory, and migrating such amount of memory may lead to >> a sudden severe performance drop lasting tens of seconds >> that some certain workloads may not afford >> c) the impact of the eviction should be limited within the >> source and destination nodes >> d) cgroup interface is preferred >> >> So we come to a thought that: >> >> 1) fire up numa-services without waiting for memory migration >> 2) memory migration can be done asynchronously by using spare >> memory bandwidth >> >> AutoNUMA seems to be a solution, but its scope is global which >> violates c&d. And cpuset.memory_migrate performs in a synchronous > > I don't think d) in itself is a valid requirement. How does it violate c)? > >> fashion which breaks a&b. So a mixture of them, the new cgroup2 >> interface cpuset.mems.migration, is introduced. >> >> The new cpuset.mems.migration supports three modes: >> >> - "none" mode, meaning migration disabled >> - "sync" mode, which is exactly the same as the cgroup v1 >> interface cpuset.memory_migrate >> - "lazy" mode, when walking through all the pages, unlike >> cpuset.memory_migrate, it only sets pages to protnone, >> and numa faults triggered by later touch will handle the >> movement. > > cpuset is already involved in NUMA allocation but it always felt like > something bolted on - it's weird to have cpu to NUMA node settings at global > level and then to have possibly conflicting direct NUMA configuration via > cpuset. My preference would be putting as much configuration as possible on > the mm / autonuma side and let cpuset's node confinements further restrict > their operations rather than cpuset having its own set of policy > configurations. > > Johannes, what are your thoughts? > > Thanks. >
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