On Thu, Aug 19, 2010 at 10:58:25AM -0400, Trond Myklebust wrote: > To me that sounds fine. I've also been trying to wrap my head around the > differences between 'nonblocking', 'for_background', 'for_reclaim' and > 'for_kupdate' and how the filesystem is supposed to treat them. Yeah, it's not clear to me either. for_background is in fact only used in nfs, for the priority and the nfs_commit_inode flags, for_kupdate is only used in nfs, and in a really weird spot in btrfs, and for_reclaim is used in nfs, and two places in nilfs2 and in shmemfs. > Aside from the above, I've used 'for_reclaim', 'for_kupdate' and > 'for_background' in order to adjust the RPC request's queuing priority > (high in the case of 'for_reclaim' and low for the other two). Right now writepage calls to the filesystem can come from various places: - the flusher threads - VM reclaim (kswapd, memcg, direct reclaim) - memory migration - filemap_fdatawrite & other calls directly from FS code, also including fsync We have WB_SYNC_ALL set for the second, data integrity pass when doing a sync from the flusher threads, and when doing data integrity writes from fs context (most fsync but also a few others). All these obviously are high priority. It's not too easy to set priorities for the others in my opinion. -- 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>