On Thu, Jun 28, 2012 at 06:52:56AM -0400, Brian Foster wrote: > xfsaild idle mode logic currently leads to a couple hangs: > > 1.) If xfsaild is rescheduled in during an incremental scan > (i.e., tout != 0) and the target has been updated since > the previous run, we can hit the new target and go into > idle mode with a still populated ail. > 2.) A wake up is only issued when the target is pushed forward. > The wake up can race with xfsaild if it is currently in the > process of entering idle mode, causing future wake up > events to be lost. > > These hangs have been reproduced and verified as fixed by > running xfstests 273 in a loop on a slightly modified upstream > kernel. The kernel is modified to re-enable idle mode as > previously implemented (when count == 0) and with a revert of > commit 670ce93f, which includes performance improvements that > make this harder to reproduce. > > The solution, the algorithm for which has been outlined by > Dave Chinner, is to modify xfsaild to enter idle mode only when > the ail is empty and the push target has not been moved forward > since the last push. > > Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx> Looks OK to me, and hasn't caused any problems here. Final question - did you confirm with powertop that the xfsaild is no longer causing wakeups a minute or two after you stop writing to the filesystem? (I haven't yet) Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx> -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
