On Wed, Aug 03, 2011 at 10:49:03PM +0200, Jan Kara wrote: > > Hi, > > at one of customer's machines, I've spotted an issue that sync(1) called > after writing a single huge file has been achieving rather low throughput. After > debugging this with blktrace, I've found that the culprit was in flusher thread > racing with page writeout happening from XFS sync code. The patches below helped > that case. Although they are not a complete solution, I belive they are useful > anyway so please consider merging them... We currently have three calls to xfs_flush_pages with XBF_ASYNC set: - xfs_setattr_size - xfs_sync_inode_data - xfs_release The first one actually is a synchronous writeout, just implemented in a rather odd way by doing the xfs_ioend_wait right after it, so your change is actively harmful for it. The second is only called from xfs_flush_worker, which is the workqueue offload when we hit ENOSPC. I can see how this might race with the writeback code, but the correct fix is to replace it with a call to writeback_inodes_sb(_if_idle) on that one is fixed to do a trylock on s_umount and thus won't deadlock. The third one is opportunistic writeout if a file got truncated down on final release. filemap_flush probably is fine here, but there's no need for a range version. If you replace it with filemap_flush please also kill the useless wrapper while you're at it. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
