| Message ID | 1426878914-15088-1-git-send-email-jeff.layton@primarydata.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mar 20, 2015, at 12:15 PM, Jeff Layton <jlayton@poochiereds.net> wrote: > Chuck pointed out a problem that crept in with commit 6ffa30d3f734 (nfs: > don't call blocking operations while !TASK_RUNNING). Linux counts tasks > in uninterruptible sleep against the load average, so this caused the > system's load average to be pinned at at least 1 when there was a > NFSv4.1+ mount active. > > Not a huge problem, but it's probably worth fixing before we get too > many complaints about it. This patch converts the code back to use > TASK_INTERRUPTIBLE sleep, simply has it flush any signals on each loop > iteration. In practice no one should really be signalling this thread at > all, so I think this is reasonably safe. > > With this change, there's also no need to game the hung task watchdog so > we can also convert the schedule_timeout call back to a normal schedule. > > Cc: <stable@vger.kernel.org> > Reported-by: Chuck Lever <chuck.lever@oracle.com> > Signed-off-by: Jeff Layton <jeff.layton@primarydata.com> Thanks for the quick response, Jeff. I applied this on top of the first patch, mounted a test filesystem with NFSv4.1, and confirmed that the backchannel service is responsive. Load average on the client at idle is now 0.01. Tested-by: Chuck Lever <chuck.lever@oracle.com> Nit: I’d add a Fixes: commit 6ffa30d3f734 (“nfs: don't call blocking . . .”) tag. > --- > fs/nfs/callback.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c > index 351be9205bf8..8d129bb7355a 100644 > --- a/fs/nfs/callback.c > +++ b/fs/nfs/callback.c > @@ -128,7 +128,7 @@ nfs41_callback_svc(void *vrqstp) > if (try_to_freeze()) > continue; > > - prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_UNINTERRUPTIBLE); > + prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE); > spin_lock_bh(&serv->sv_cb_lock); > if (!list_empty(&serv->sv_cb_list)) { > req = list_first_entry(&serv->sv_cb_list, > @@ -142,10 +142,10 @@ nfs41_callback_svc(void *vrqstp) > error); > } else { > spin_unlock_bh(&serv->sv_cb_lock); > - /* schedule_timeout to game the hung task watchdog */ > - schedule_timeout(60 * HZ); > + schedule(); > finish_wait(&serv->sv_cb_waitq, &wq); > } > + flush_signals(current); > } > return 0; > } > -- > 2.1.0 > -- Chuck Lever chuck[dot]lever[at]oracle[dot]com -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c index 351be9205bf8..8d129bb7355a 100644 --- a/fs/nfs/callback.c +++ b/fs/nfs/callback.c @@ -128,7 +128,7 @@ nfs41_callback_svc(void *vrqstp) if (try_to_freeze()) continue; - prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_UNINTERRUPTIBLE); + prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE); spin_lock_bh(&serv->sv_cb_lock); if (!list_empty(&serv->sv_cb_list)) { req = list_first_entry(&serv->sv_cb_list, @@ -142,10 +142,10 @@ nfs41_callback_svc(void *vrqstp) error); } else { spin_unlock_bh(&serv->sv_cb_lock); - /* schedule_timeout to game the hung task watchdog */ - schedule_timeout(60 * HZ); + schedule(); finish_wait(&serv->sv_cb_waitq, &wq); } + flush_signals(current); } return 0; }
Chuck pointed out a problem that crept in with commit 6ffa30d3f734 (nfs: don't call blocking operations while !TASK_RUNNING). Linux counts tasks in uninterruptible sleep against the load average, so this caused the system's load average to be pinned at at least 1 when there was a NFSv4.1+ mount active. Not a huge problem, but it's probably worth fixing before we get too many complaints about it. This patch converts the code back to use TASK_INTERRUPTIBLE sleep, simply has it flush any signals on each loop iteration. In practice no one should really be signalling this thread at all, so I think this is reasonably safe. With this change, there's also no need to game the hung task watchdog so we can also convert the schedule_timeout call back to a normal schedule. Cc: <stable@vger.kernel.org> Reported-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Jeff Layton <jeff.layton@primarydata.com> --- fs/nfs/callback.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)