On Fri 01-04-22 09:58:59, Roman Gushchin wrote: > On Fri, Apr 01, 2022 at 03:49:19PM +0200, Michal Hocko wrote: > > On Thu 31-03-22 10:25:23, Roman Gushchin wrote: > > > On Thu, Mar 31, 2022 at 08:41:51AM +0000, Yosry Ahmed wrote: > > [...] > > > > - A similar per-node interface can also be added to support proactive > > > > reclaim and reclaim-based demotion in systems without memcg. > > > > > > Maybe an option to specify a timeout? That might simplify the userspace part. > > > > What do you mean by timeout here? Isn't > > timeout $N echo $RECLAIM > .... > > > > enough? > > It's nice and simple when it's a bash script, but when it's a complex > application trying to do the same, it quickly becomes less simple and > likely will require a dedicated thread to avoid blocking the main app > for too long and a mechanism to unblock it by timer/when the need arises. > > In my experience using correctly such semi-blocking interfaces (semi- because > it's not clearly defined how much time the syscall can take and whether it > makes sense to wait longer) is tricky. We have the same approach to setting other limits which need to perform the reclaim. Have we ever hit that as a limitation that would make userspace unnecessarily too complex? -- Michal Hocko SUSE Labs
