Messages in this thread Patch in this message | | | From | lizf@kernel ... | Subject | [PATCH 3.4 054/146] nfs: fix high load average due to callback thread sleeping | Date | Tue, 15 Sep 2015 17:02:49 +0800 |
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From: Jeff Layton <jlayton@poochiereds.net>
3.4.109-rc1 review patch. If anyone has any objections, please let me know.
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commit 5d05e54af3cdbb13cf19c557ff2184781b91a22c upstream.
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.
Reported-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Jeff Layton <jeff.layton@primarydata.com> Tested-by: Chuck Lever <chuck.lever@oracle.com> Fixes: commit 6ffa30d3f734 (“nfs: don't call blocking . . .”) Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> [lizf: Backported to 3.4: adjust context] Signed-off-by: Zefan Li <lizefan@huawei.com> --- 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 07c056c..0184e91 100644 --- a/fs/nfs/callback.c +++ b/fs/nfs/callback.c @@ -149,7 +149,7 @@ nfs41_callback_svc(void *vrqstp) set_freezable(); while (!kthread_should_stop()) { - 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, @@ -163,10 +163,10 @@ 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; } -- 1.9.1
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