Greetings, While doing some generic scheduler latency testing, I stumbled onto $subject. To reproduce this, I simply nfs mount my box, cd to one of it's spinning rust buckets, and do bonnie -s <ramsize>. With nothing else going on in the box, I've hit > 100ms wakeup latencies.
(nouveau apparently also thinks this is uncool, and whimpers) .... kworker/-7421 0.N.. 82893us : nfs_release_request <-nfs_commit_release_pages kworker/-7421 0.N.. 82893us : nfs_unlock_and_release_request <-nfs_commit_release_pages kworker/-7421 0.N.. 82893us : nfs_unlock_request <-nfs_unlock_and_release_request kworker/-7421 0.N.. 82893us : nfs_page_group_destroy <-nfs_commit_release_pages kworker/-7421 0.N.. 82893us : nfs_page_group_sync_on_bit <-nfs_page_group_destroy kworker/-7421 0.N.. 82893us : nfs_page_group_lock <-nfs_page_group_sync_on_bit kworker/-7421 0.N.. 82893us : nfs_page_group_unlock <-nfs_page_group_sync_on_bit kworker/-7421 0.N.. 82893us : nfs_free_request <-nfs_page_group_destroy kworker/-7421 0.N.. 82893us : nfs_put_lock_context <-nfs_free_request kworker/-7421 0.N.. 82893us : put_nfs_open_context <-nfs_free_request kworker/-7421 0.N.. 82893us : __put_nfs_open_context <-nfs_free_request kworker/-7421 0.N.. 82894us : kmem_cache_free <-nfs_page_group_destroy kworker/-7421 0.N.. 82894us : __slab_free <-kmem_cache_free kworker/-7421 0.N.. 82894us : clear_wb_congested <-nfs_commit_release_pages kworker/-7421 0.N.. 82894us : nfs_init_cinfo <-nfs_commit_release_pages kworker/-7421 0.N.. 82894us : nfs_init_cinfo_from_inode <-nfs_commit_release_pages kworker/-7421 0.N.. 82894us : nfs_commit_end <-nfs_commit_release_pages kworker/-7421 0.N.. 82894us : nfs_commitdata_release <-rpc_free_task kworker/-7421 0.N.. 82894us : put_nfs_open_context <-nfs_commitdata_release kworker/-7421 0.N.. 82894us : __put_nfs_open_context <-nfs_commitdata_release kworker/-7421 0.N.. 82895us : mempool_free <-rpc_free_task kworker/-7421 0.N.. 82895us : mempool_free_slab <-rpc_free_task kworker/-7421 0.N.. 82895us : kmem_cache_free <-rpc_free_task kworker/-7421 0.N.. 82895us : ___might_sleep <-process_one_work kworker/-7421 0.N.. 82895us : _cond_resched <-process_one_work kworker/-7421 0dN.1 82895us : rcu_note_context_switch <-__schedule
