On 2014-09-03 20:08, Elliott, Robert (Server Storage) wrote:
-----Original Message-----
From: Jens Axboe [mailto:axboe@xxxxxxxxx]
Sent: Wednesday, September 03, 2014 8:34 PM
To: Elliott, Robert (Server Storage); fio@xxxxxxxxxxxxxxx;
scameron@xxxxxxxxxxxxxxxxxx
Subject: Re: [PATCH] fio: fix hangs due to iodepth_low
On 2014-09-03 18:23, Robert Elliott wrote:
With some combinations of iodepth, iodepth_batch,
iodepth_batch_complete,
and io_depth_low, do_io hangs after reaping the first set of
completions
since io_u_queued_complete is called requesting more completions than
td->cur_depth.
Example printing min_evts and td->cur_depth in the do/while loop:
waiting on min=96 cd=627
waiting on min=96 cd=531
waiting on min=96 cd=435
waiting on min=96 cd=339
waiting on min=96 cd=243
waiting on min=96 cd=147
waiting on min=96 cd=51
Jobs: 12 (f=12): [r(12)] [43.8% done] [0KB/0KB/0KB /s] [0/0/0 iops]
[eta 00m:09s]
...
Jobs: 12 (f=12): [r(12)] [0.0% done] [0KB/0KB/0KB /s] [0/0/0 iops]
[eta 2863d:18h:28m:38s]
<fio never exits>
Fix this by adjusting min_evts to the current_depth if that is
smaller.
Tested with a jobfile including:
iodepth=1011
iodepth_batch=96
iodepth_batch_complete=96
iodepth_low=1
runtime=15
time_based
Made the same change to do_verify, but not tested there.
Signed-off-by: Robert Elliott <elliott@xxxxxx>
---
backend.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/backend.c b/backend.c
index 7cb0a39..ce97f6d 100644
--- a/backend.c
+++ b/backend.c
@@ -606,6 +606,8 @@ reap:
* and do the verification on them through
* the callback handler
*/
+ if (min_events < td->cur_depth)
+ min_events = td->cur_depth;
Did you reverse these? From the description and debug output, seems it
should be:
if (min_events > td->cur_depth)
min_events = td->cur_depth;
and we should probably put this logic in io_u_queued_complete(), I think
that would be a safer alternative instead of near the callers.
--
Jens Axboe
Sorry, yes - I didn't put it back right after adding code
to inject the error.
I will send an updated patch tomorrow putting the check into
io_u_queued_complete (if that has access to td).
Thanks, much appreciated! The fix is the easy part, the diagnosing was
the hard part.
--
Jens Axboe
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