From: Peter Lieven <pl@kamp.de>
To: Kevin Wolf <kwolf@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>
Cc: qemu-devel <qemu-devel@nongnu.org>, qemu block <qemu-block@nongnu.org>
Subject: Re: [Qemu-devel] [Qemu-block] RFC cdrom in own thread?
Date: Thu, 18 Jun 2015 08:39:05 +0200 [thread overview]
Message-ID: <55826789.6080008@kamp.de> (raw)
In-Reply-To: <20150617083539.GA4202@noname.str.redhat.com>
Am 17.06.2015 um 10:35 schrieb Kevin Wolf:
> Am 16.06.2015 um 17:34 hat Stefan Hajnoczi geschrieben:
>> On Tue, Jun 16, 2015 at 3:44 PM, Peter Lieven <pl@kamp.de> wrote:
>>> I wonder how difficult it would be to have the IDE CDROM run in its own
>>> thread?
>>> We usually have ISOs mounted on an NFS share as CDROM. Problem: If the NFS
>>> Share
>>> goes down, it takes down monitor, qmp, vnc etc. with it.
>>>
>>> Maybe its already possible to do this via cmdline args?
>>>
>>> Any ideas, comments?
>> If QEMU hangs in the read/write/flush/discard code path due to NFS
>> downtime it is a bug.
>>
>> QEMU is expected to hang in open/reopen because those are performed in
>> a blocking fashion.
>>
>> Which of these cases applies to what you are seeing? Maybe it can be fixed.
> Don't forget bdrv_drain_all(), which is called a lot by the monitor. So
> no matter what you do (and this includes moving to a thread as in a
> hypothetical "ATAPI dataplane"), you end up with a hang sooner or later.
It seems like the mainloop is waiting here:
#0 0x00007ffff606c89c in __lll_lock_wait ()
from /lib/x86_64-linux-gnu/libpthread.so.0
No symbol table info available.
#1 0x00007ffff6068065 in _L_lock_858 ()
from /lib/x86_64-linux-gnu/libpthread.so.0
No symbol table info available.
#2 0x00007ffff6067eba in pthread_mutex_lock ()
from /lib/x86_64-linux-gnu/libpthread.so.0
No symbol table info available.
#3 0x00005555559f2557 in qemu_mutex_lock (mutex=0x555555ed6d40)
at util/qemu-thread-posix.c:76
err = 0
__func__ = "qemu_mutex_lock"
#4 0x00005555556306ef in qemu_mutex_lock_iothread ()
at /usr/src/qemu-2.2.0/cpus.c:1123
No locals.
#5 0x0000555555954a87 in os_host_main_loop_wait (timeout=79413589)
at main-loop.c:242
ret = 1
spin_counter = 0
#6 0x0000555555954b5f in main_loop_wait (nonblocking=0) at main-loop.c:494
ret = 15
timeout = 4294967295
timeout_ns = 79413589
#7 0x000055555575e702 in main_loop () at vl.c:1882
nonblocking = false
last_io = 1
Peter
next prev parent reply other threads:[~2015-06-18 6:39 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <55803637.3060607@kamp.de>
2015-06-16 15:34 ` [Qemu-devel] [Qemu-block] RFC cdrom in own thread? Stefan Hajnoczi
2015-06-17 8:35 ` Kevin Wolf
2015-06-18 6:03 ` Peter Lieven
2015-06-18 6:57 ` Markus Armbruster
2015-06-18 6:39 ` Peter Lieven [this message]
2015-06-18 6:59 ` Paolo Bonzini
2015-06-18 7:03 ` Peter Lieven
2015-06-18 7:12 ` Peter Lieven
2015-06-18 7:45 ` Kevin Wolf
2015-06-18 8:30 ` Peter Lieven
2015-06-18 8:42 ` Kevin Wolf
2015-06-18 9:29 ` Peter Lieven
2015-06-18 9:36 ` Stefan Hajnoczi
2015-06-18 9:53 ` Peter Lieven
2015-06-19 13:14 ` Peter Lieven
2015-06-22 9:25 ` Stefan Hajnoczi
2015-06-22 13:09 ` Peter Lieven
2015-06-22 21:54 ` John Snow
2015-06-23 6:36 ` Peter Lieven
2015-08-14 13:43 ` Peter Lieven
2015-08-14 14:08 ` Kevin Wolf
2015-08-14 14:21 ` Peter Lieven
2015-08-14 14:45 ` Peter Lieven
2015-08-15 19:02 ` Peter Lieven
2015-06-18 10:17 ` Peter Lieven
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