> > We surely need 1 set aside for each level of that stack that will > > potentially consume one. 1 should be enough for the generic pool, and > > then clones will use a separate pool. So md and friends should really > > have a pool per device, so that stacking will always work properly. > > Agreed for the deadlock problem. > > > There should be no throughput concerns, it should purely be a safe guard > > measure to prevent us deadlocking when doing IO for reclaim. > > It's easy to verify whether the minimal size will have negative > impacts on IO throughput. In Torsten's case, increase BIO_POOL_SIZE > by one and check how it performs. Sorry it seems simply increasing BIO_POOL_SIZE is not enough to fix possible deadlocks. We need adding new mempool(s). Because when there BIO_POOL_SIZE=2 and there are two concurrent reclaimers each take 1 reservation, they will deadlock each other when trying to take the next bio at the raid1 level. Thanks, Fengguang -- 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>