On Thu, Apr 15, 2010 at 01:35:17PM +0900, KOSAKI Motohiro wrote: > > Hi > > > > > How about this? For now, we stop direct reclaim from doing writeback > > > only on order zero allocations, but allow it for higher order > > > allocations. That will prevent the majority of situations where > > > direct reclaim blows the stack and interferes with background > > > writeout, but won't cause lumpy reclaim to change behaviour. > > > This reduces the scope of impact and hence testing and validation > > > the needs to be done. > > > > Tend to agree. but I would proposed slightly different algorithm for > > avoind incorrect oom. > > > > for high order allocation > > allow to use lumpy reclaim and pageout() for both kswapd and direct reclaim > > > > for low order allocation > > - kswapd: always delegate io to flusher thread > > - direct reclaim: delegate io to flusher thread only if vm pressure is low > > > > This seems more safely. I mean Who want see incorrect oom regression? > > I've made some pathes for this. I'll post it as another mail. > > Now, kernel compile and/or backup operation seems keep nr_vmscan_write==0. > Dave, can you please try to run your pageout annoying workload? It's just as easy for you to run and observe the effects. Start with a VM with 1GB RAM and a 10GB scratch block device: # mkfs.xfs -f /dev/<blah> # mount -o logbsize=262144,nobarrier /dev/<blah> /mnt/scratch in one shell: # while [ 1 ]; do dd if=/dev/zero of=/mnt/scratch/foo bs=1024k ; done in another shell, if you have fs_mark installed, run: # ./fs_mark -S0 -n 100000 -F -s 0 -d /mnt/scratch/0 -d /mnt/scratch/1 -d /mnt/scratch/3 -d /mnt/scratch/2 & otherwise run a couple of these in parallel on different directories: # for i in `seq 1 1 100000`; do echo > /mnt/scratch/0/foo.$i ; done Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>