Hi all, Storage/posix does syscalls on backend filesystem holding inode->lock. This is bad as it is a lock global to the inode and can cause unnecessary contention with unrelated translators doing unrelated operations (like inode_ctx_get etc). I've discussed one such issue in [2]. A quick git grep on "inode->lock" in storage/posix gave following results:
* posix_writev - GLUSTERFS_WRITE_IS_APPEND - looks like used by arbiter/afr. GLUSTERFS_WRITE_UPDATE_ATOMIC - looks like used by shard * posix_fd_ctx_get - resolves gfid handle (which can involve multiple readlinks and lstats) in inode->lock. Though the cost is only once when fd-ctx is freshly created. * code that maintains pgfid xattrs - executed in various dentry modification fops like mkdir, create, mknod, unlink, rename, link etc * code that uses GET_LINK_COUNT - looks like used by shard and EC. Note that this code is executed during rename/unlink. * posix_create_link_if_gfid_exists - looks like used by afr entry selfheal * posix_(f)xattrop - various xlators like afr, marker during different fops. The question here is can we've synchronization using a lock visible only to storage/posix so that contention is localized (like [1])? [1] https://review.gluster.org/16462 [2] http://lists.gluster.org/pipermail/gluster-devel/2017-January/051936.html regards, Raghavendra _______________________________________________ Gluster-devel mailing list Gluster-devel@gluster.org http://lists.gluster.org/mailman/listinfo/gluster-devel
