On Mon, Dec 18, 2017 at 04:31:52PM +0100, Mike Galbraith wrote: > On Mon, 2017-12-18 at 16:17 +0100, Mike Galbraith wrote: > > > > .... > > 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 > > diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c > index d0543e19098a..b42bf3b21e05 100644 > --- a/fs/nfs/pagelist.c > +++ b/fs/nfs/pagelist.c > @@ -428,6 +428,7 @@ void nfs_free_request(struct nfs_page *req) > /* Release struct file and open context */ > nfs_clear_request(req); > nfs_page_free(req); > + cond_resched(); > } > > void nfs_release_request(struct nfs_page *req) This probably just shows I don't understand the issues, but: isn't this the job of preemption? If we're not holding any locks that would prevent scheduling here, shouldn't latency-sensitive users be building preemptible kernels and letting the scheduler take care of this? It seems unfortunate to require explicit cond_resched()s allovers. Like I say, I don't really understand the issues here, so it's more a question than an objection.... (I don't know any reason a cond_resched() would be bad there.) --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
