On Fri, 26 Oct 2007 14:05:47 -0700 Martin Bligh <[EMAIL PROTECTED]> wrote:
> > Martin was talking about some mad scheme wherin you'd create a bunch of > > pseudo files (say, /proc/foo/0, /proc/foo/1, ..., /proc/foo/9) and each one > > would become "ready" when the MM scanning priority reaches 10%, 20%, ... > > 100%. > > > > Obviously there would need to be a lot of abstraction to unhook a permanent > > userspace feature from a transient kernel implementation, but the basic > > idea is that a process which wants to know when the VM is getting into the > > orange zone would select() on the file "7" and a process which wants to > > know when the VM is getting into the red zone would select on file "9". > > > > It get more complicated with NUMA memory nodes and cgroup memory > > controllers. > > We ended up not doing that, but making a scanner that saw what > percentage of the LRU was touched in the last n seconds, and > printing that to userspace to deal with. > > Turns out priority is a horrible metric to use for this - it > stays at default for ages, then falls off a cliff far too > quickly to react to. Sure, but in terms of high-level userspace interface, being able to select() on a group of priority buckets (spread across different nodes, zones and cgroups) seems a lot more flexible than any signal-based approach we could come up with. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
