On Fri, Apr 27, 2012 at 11:40:34AM -0400, Vivek Goyal wrote: > On Fri, Apr 27, 2012 at 08:02:17AM -0700, Tejun Heo wrote: > > Hello, > > > > On Fri, Apr 27, 2012 at 10:54:01AM -0400, Jeff Moyer wrote: > > > > This patch implements per-blkg request_list. Each blkg has its own > > > > request_list and any IO allocates its request from the matching blkg > > > > making blkcgs completely isolated in terms of request allocation. > > > > > > So, nr_requests is now actually nr_requests * # of blk cgroups. Is that > > > right? Are you at all concerned about the amount of memory that can be > > > tied up as the number of cgroups increases? > > > > Yeah, I thought about it and I don't think there's a single good > > solution here. The other extreme would be splitting nr_requests by > > the number of cgroups but that seems even worse - each cgroup should > > be able to hit maximum throughput. Given that a lot of workloads tend > > to regulate themselves before hitting nr_requests, I think it's best > > to leave it as-is and treat each cgroup as having separate channel for > > now. It's a configurable parameter after all. > > So on a slow device a malicious application can easily create thousands > of group, queue up tons of IO and create unreclaimable memory easily? > Sounds little scary. Malicious application may just jack up nr_requests. Thanks. -- tejun -- 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
