lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Fri, 2 Dec 2022 15:51:05 -0800 From: Shakeel Butt <shakeelb@...gle.com> To: Mina Almasry <almasrymina@...gle.com> Cc: Tejun Heo <tj@...nel.org>, Zefan Li <lizefan.x@...edance.com>, Johannes Weiner <hannes@...xchg.org>, Jonathan Corbet <corbet@....net>, Michal Hocko <mhocko@...nel.org>, Roman Gushchin <roman.gushchin@...ux.dev>, Muchun Song <songmuchun@...edance.com>, Andrew Morton <akpm@...ux-foundation.org>, Huang Ying <ying.huang@...el.com>, Yang Shi <yang.shi@...ux.alibaba.com>, Yosry Ahmed <yosryahmed@...gle.com>, weixugc@...gle.com, fvdl@...gle.com, Michal Hocko <mhocko@...e.com>, bagasdotme@...il.com, cgroups@...r.kernel.org, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org Subject: Re: [PATCH v3] mm: Add nodes= arg to memory.reclaim On Fri, Dec 2, 2022 at 2:37 PM Mina Almasry <almasrymina@...gle.com> wrote: > > The nodes= arg instructs the kernel to only scan the given nodes for > proactive reclaim. For example use cases, consider a 2 tier memory system: > > nodes 0,1 -> top tier > nodes 2,3 -> second tier > > $ echo "1m nodes=0" > memory.reclaim > > This instructs the kernel to attempt to reclaim 1m memory from node 0. > Since node 0 is a top tier node, demotion will be attempted first. This > is useful to direct proactive reclaim to specific nodes that are under > pressure. > > $ echo "1m nodes=2,3" > memory.reclaim > > This instructs the kernel to attempt to reclaim 1m memory in the second tier, > since this tier of memory has no demotion targets the memory will be > reclaimed. > > $ echo "1m nodes=0,1" > memory.reclaim > > Instructs the kernel to reclaim memory from the top tier nodes, which can > be desirable according to the userspace policy if there is pressure on > the top tiers. Since these nodes have demotion targets, the kernel will > attempt demotion first. > > Since commit 3f1509c57b1b ("Revert "mm/vmscan: never demote for memcg > reclaim""), the proactive reclaim interface memory.reclaim does both > reclaim and demotion. Reclaim and demotion incur different latency costs > to the jobs in the cgroup. Demoted memory would still be addressable > by the userspace at a higher latency, but reclaimed memory would need to > incur a pagefault. > > The 'nodes' arg is useful to allow the userspace to control demotion > and reclaim independently according to its policy: if the memory.reclaim > is called on a node with demotion targets, it will attempt demotion first; > if it is called on a node without demotion targets, it will only attempt > reclaim. > > Acked-by: Michal Hocko <mhocko@...e.com> > Signed-off-by: Mina Almasry <almasrymina@...gle.com> > Acked-by: Shakeel Butt <shakeelb@...gle.com>
Powered by blists - more mailing lists