Nir Soffer has uploaded a new change for review.
Change subject: blockSD: Fix busy loop when zeroing image volumes
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blockSD: Fix busy loop when zeroing image volumes
We used to wait on the wrong file descriptor (stdout, writing to image),
using the wrong mask (EPOLLHUP when using poll).
The result - vdsm consume 100% cpu when zeroing image:
Tue May 17 01:33:57 2016 vdsmd.prof
310515403 function calls (310560288 primitive calls) in 377.096 seconds
Ordered by: internal time
List reduced from 3173 to 20 due to restriction <20>
ncalls tottime percall cumtime percall filename:lineno(function)
37946430 74.674 0.000 257.590 0.000 commands.py:302(AsyncProc.wait)
1 65.338 65.338 357.741 357.741 blockSD.py:229(zeroImgVolumes)
37947222 54.932 0.000 54.932 0.000 posix:0(waitpid)
37946448 38.780 0.000 159.845 0.000
commands.py:284(AsyncProc.returncode)
37946441 38.363 0.000 93.210 0.000
subprocess.py:1344(CPopen._internal_poll)
38034684 35.044 0.000 35.045 0.000 __builtin__:0(poll)
37946441 27.856 0.000 121.065 0.000 subprocess.py:803(CPopen.poll)
75928952 23.096 0.000 23.096 0.000 time:0(time)
Fixed by watching stderr, where the stats are written at the end, using POLLIN.
This fix is mainly for 3.6, for 4.0 we want to drop this buggy code and
replace it with simpler thread based code.
Change-Id: I7f5ec5faefb6840f1bd5348b93cc784d0aff8690
Signed-off-by: Nir Soffer <nsof...@redhat.com>
---
M vdsm/storage/blockSD.py
1 file changed, 2 insertions(+), 2 deletions(-)
git pull ssh://gerrit.ovirt.org:29418/vdsm refs/changes/41/57541/1
diff --git a/vdsm/storage/blockSD.py b/vdsm/storage/blockSD.py
index d03bc0e..a9c82f5 100644
--- a/vdsm/storage/blockSD.py
+++ b/vdsm/storage/blockSD.py
@@ -246,9 +246,9 @@
poller = select.poll()
for volUUID in volUUIDs:
proc = _zeroVolume(sdUUID, volUUID)
- fd = proc.stdout.fileno()
+ fd = proc.stderr.fileno()
zerofds[fd] = ProcVol(proc, volUUID)
- poller.register(fd, select.EPOLLHUP)
+ poller.register(fd, select.POLLIN)
# Wait until all the asyncs procs return
# Yes, this is a potentially infinite loop. Kill the vdsm task.
--
To view, visit https://gerrit.ovirt.org/57541
To unsubscribe, visit https://gerrit.ovirt.org/settings
Gerrit-MessageType: newchange
Gerrit-Change-Id: I7f5ec5faefb6840f1bd5348b93cc784d0aff8690
Gerrit-PatchSet: 1
Gerrit-Project: vdsm
Gerrit-Branch: master
Gerrit-Owner: Nir Soffer <nsof...@redhat.com>
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