On 05/17/2017 05:47 PM, Tejun Heo wrote: > Hello, Waiman. > > On Mon, May 15, 2017 at 09:34:10AM -0400, Waiman Long wrote: >> The current thread mode semantics aren't sufficient to fully support >> threaded controllers like cpu. The main problem is that when thread >> mode is enabled at root (mainly for performance reason), all the >> non-threaded controllers cannot be supported at all. >> >> To alleviate this problem, the roles of thread root and threaded >> cgroups are now further separated. Now thread mode can only be enabled >> on a non-root leaf cgroup whose parent will then become the thread >> root. All the descendants of a threaded cgroup will still need to be >> threaded. All the non-threaded resource will be accounted for in the >> thread root. Unlike the previous thread mode, however, a thread root >> can have non-threaded children where system resources like memory >> can be further split down the hierarchy. >> >> Now we could have something like >> >> R -- A -- B >> \ >> T1 -- T2 >> >> where R is the thread root, A and B are non-threaded cgroups, T1 and >> T2 are threaded cgroups. The cgroups R, T1, T2 form a threaded subtree >> where all the non-threaded resources are accounted for in R. The no >> internal process constraint does not apply in the threaded subtree. >> Non-threaded controllers need to properly handle the competition >> between internal processes and child cgroups at the thread root. >> >> This model will be flexible enough to support the need of the threaded >> controllers. > I do like the approach and it does address the issue with requiring at > least one level of nesting for the thread mode to be used with other > controllers. I need to think a bit more about it and mull over what > Peterz was suggesting in the old thread. I'll get back to you soon > but I'd really prefer this and the earlier related patches to be in > its own patchset so that we aren't dealing with different things at > the same time. > > Thanks. > I have studied the email exchanges with your original thread mode patchset. This patchset is aimed to hopefully address all the concerns that Peterz has. This enhanced thread mode should address a big part of the concern. However, I am not sure if this patch, by itself, is enough to address all his concerns. That is why I also include 2 other major changes in the next 2 patches. My goal is to move forward to allow all controllers to be enabled for v2 eventually. We are not there yet, but I hope this patchset can move thing forward meaningfully. Regards, Longman -- 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
