Hi, > > On Tue, Apr 22 2008, Hirokazu Takahashi wrote: > > > Hi, > > > > > > Sorry, these patches are for linux-2.6.25. > > > > > > > This series of patches make the block I/O layer and the I/O schedulers > > > > be able to determine the right io_context of every I/O. > > > > > > > > The current implementation of the block I/O layer and the I/O schedulers > > > > assume that the current process is the one which issued the given I/O, > > > > then use the io_context of this process to control the I/O. > > > > But this assumption isn't quite right because several kernel threads > > > > will handle I/O requests on behalf of the processes which originated them. > > > > This often happens when you want to use device mapper modules. > > > > > > > > The patches make every bio has a pointer to an io_context, which will > > > > be set when it is allocated or cloned. So it makes it possible to find > > > > the right io_context from any bio at any place. > > > > > > > > I'm waiting for your comments. > > > > Can you give a brief summary of what you need this stuff for? > > > > I am not sure if this the intended application, but I have been > looking at supporting ionice over software-raid and this series seems > like a necessary first step. Yes, the intention is to make ionice be able to work correctly over device mapper modules such as software-raid and the multipath driver. This mechanism is needed since quite a few device mapper modules have kernel threads, including workqueues, handle I/O requests. And I also have a plan to use this new feature for block I/O bandwidth control based on cgroup with some enhancement. With this feature, we can also trace the iocontext of the process or cgroup which made a certain page dirtied. Thank you, Hirokazu Takahashi. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
