From: Jeff Layton Date: Fri, 20 Mar 2015 19:15:14 +0000 (-0400) Subject: nfs: fix high load average due to callback thread sleeping X-Git-Tag: v5.15~15856^2~14 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=5d05e54af3cdbb13cf19c557ff2184781b91a22c;p=platform%2Fkernel%2Flinux-starfive.git nfs: fix high load average due to callback thread sleeping 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: Reported-by: Chuck Lever Signed-off-by: Jeff Layton Tested-by: Chuck Lever Fixes: commit 6ffa30d3f734 (“nfs: don't call blocking . . .”) Signed-off-by: Trond Myklebust --- diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c index 351be920..8d129bb 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; }