Hi all,
That's a respin of the previous patchset that tried to add a new 'cross' event type, which would trigger whenever value crosses a user-specified threshold both ways, i.e. from a lesser values side to a greater values side, and vice versa.
We use the event type in an userspace low-memory killer: we get a notification when memory becomes low, so we start freeing memory by killing unneeded processes, and we get notification when memory hits the threshold from another side, so we know that we freed enough of memory.
There's also a fix for a bug that makes kernel upset about sleeping in the atomic context.
Per Pekka's comments here comes v2. Changes:
- Added a one-shot mode plus a greater-than attribute, the two additions makes the equivalent of the cross-event type. - In the bugfix patch I added some comments about implementation details of the lock-free logic. Also, in the previous version of the fix I forgot to remove 'struct mutex' form the 'struct vmevent_watch', this is now cleaned up.
As usual, the patches are against
git://github.com/penberg/linux.git vmevent/core
Thanks!