On Fri 11-03-16 11:34:40, Vladimir Davydov wrote: > On Thu, Mar 10, 2016 at 03:50:13PM -0500, Johannes Weiner wrote: > > When setting memory.high below usage, nothing happens until the next > > charge comes along, and then it will only reclaim its own charge and > > not the now potentially huge excess of the new memory.high. This can > > cause groups to stay in excess of their memory.high indefinitely. > > > > To fix that, when shrinking memory.high, kick off a reclaim cycle that > > goes after the delta. > > I agree that we should reclaim the high excess, but I don't think it's a > good idea to do it synchronously. Currently, memory.low and memory.high > knobs can be easily used by a single-threaded load manager implemented > in userspace, because it doesn't need to care about potential stalls > caused by writes to these files. After this change it might happen that > a write to memory.high would take long, seconds perhaps, so in order to > react quickly to changes in other cgroups, a load manager would have to > spawn a thread per each write to memory.high, which would complicate its > implementation significantly. Is the complication on the managing part really an issue though. Such a manager would have to spawn a process/thread to change the .max already. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
