> 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 Thanks. Unfortunately, I don't have unused disks. So, I'll try it at (probably) next week. -- 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>