On 11/03/2012 12:06 AM, Tejun Heo wrote: > Hey, Joonsoo. > > On Sat, Nov 03, 2012 at 04:25:59AM +0900, JoonSoo Kim wrote: >> I am worrying about data cache footprint which is possibly caused by >> this patchset, especially slab implementation. >> If there are several memcg cgroups, each cgroup has it's own kmem_caches. >> When each group do slab-intensive job hard, data cache may be overflowed easily, >> and cache miss rate will be high, therefore this would decrease system >> performance highly. > > It would be nice to be able to remove such overhead too, but the > baselines for cgroup implementations (well, at least the ones that I > think important) in somewhat decreasing priority are... > > 1. Don't over-complicate the target subsystem. > > 2. Overhead when cgroup is not used should be minimal. Prefereably to > the level of being unnoticeable. > > 3. Overhead while cgroup is being actively used should be reasonable. > > If you wanna split your system into N groups and maintain memory > resource segregation among them, I don't think it's unreasonable to > ask for paying data cache footprint overhead. > > So, while improvements would be nice, I wouldn't consider overheads of > this type as a blocker. > > Thanks. > There is another thing I should add. We are essentially replicating all the allocator meta-data, so if you look at it, this is exactly the same thing as workloads that allocate from different allocators (i.e.: a lot of network structures, and a lot of dentries). In this sense, it really basically depends what is your comparison point. Full containers - the main (but not exclusive) reason for this, are more or less an alternative for virtual machines. In those, you would be allocating from a different cache because you would be getting those through a bunch of memory address translations. From this, we do a lot better, since we only change the cache you allocate from, keeping all the rest unchanged. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>