Naveen Gupta wrote: >> Paul Menage wrote: >>> On Jan 18, 2008 7:36 AM, Dhaval Giani <[EMAIL PROTECTED]> wrote: >>>> On Fri, Jan 18, 2008 at 12:41:03PM +0100, Andrea Righi wrote: >>>>> Allow to limit the block I/O bandwidth for specific process containers >>>>> (cgroups) imposing additional delays on I/O requests for those processes >>>>> that exceed the limits defined in the control group filesystem. >>>>> >>>>> Example: >>>>> # mkdir /dev/cgroup >>>>> # mount -t cgroup -oio-throttle io-throttle /dev/cgroup >>>> Just a minor nit, can't we name it as io, keeping in mind that other >>>> controllers are known as cpu and memory? >>> Or maybe "blockio"? >> Agree, blockio seems better. Not all I/O is performed on block devices >> and in this case we're considering block devices only. > > Here we want to rate limit in block layer, I would think I/O scheduler > is the place where we are in much better position to do this kind of > limiting. > > Also we are changing the behavior of application by adding sleeps to > it during request submission. Moreover, we will prevent requests from > being merged since we won't allow them to be submitted in this case. > > Since bulk of submission for writes is done in background kernel > threads and we throttle based on limits on current, we will end up > throttling these threads and not the actual processes submitting i/o.
Yep, that's true! This works for read operations only... at the very least, if I've understood well, we could throttle I/O reads in the submit_bio() path and write operations in __set_page_dirty(). But this would change the applications behavior, so probably the best approcah could be to just get I/O statistics from TASK_IO_ACCOUNTING stuff and implement task delays at the I/O scheduler layer... Thanks, -Andrea -- 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/
