diff options
Diffstat (limited to 'results/scraper/launchpad-without-comments/1831750')
| -rw-r--r-- | results/scraper/launchpad-without-comments/1831750 | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/results/scraper/launchpad-without-comments/1831750 b/results/scraper/launchpad-without-comments/1831750 new file mode 100644 index 00000000..cc5b4e3d --- /dev/null +++ b/results/scraper/launchpad-without-comments/1831750 @@ -0,0 +1,70 @@ +virtual machine cpu soft lockup when qemu attach disk + +Hi, I found a problem that virtual machine cpu soft lockup when I attach a disk to the vm in the case that + +backend storage network has a large delay or IO pressure is too large. + +1) The disk xml which I attached is: + + <disk type='block' device='lun' rawio='yes'> + <driver name='qemu' type='raw' cache='none' io='native'/> + <source dev='/dev/mapper/360022a11000c1e0a0787c23a000001cb'/> + <backingStore/> + <target dev='sdb' bus='scsi'/> + <alias name='scsi0-0-1-0'/> + <address type='drive' controller='0' bus='0' target='1' unit='0'/> + </disk> + +2) The bt of qemu main thread: + +#0 0x0000ffff9d78402c in pread64 () from /lib64/libpthread.so.0 +#1 0x0000aaaace3357d8 in pread64 (__offset=0, __nbytes=4096, __buf=0xaaaad47a5200, __fd=202) at /usr/include/bits/unistd.h:99 +#2 raw_is_io_aligned (fd=fd@entry=202, buf=buf@entry=0xaaaad47a5200, len=len@entry=4096) at block/raw_posix.c:294 +#3 0x0000aaaace33597c in raw_probe_alignment (bs=bs@entry=0xaaaad32ea920, fd=202, errp=errp@entry=0xfffffef7a330) at block/raw_posix.c:349 +#4 0x0000aaaace335a48 in raw_refresh_limits (bs=0xaaaad32ea920, errp=0xfffffef7a330) at block/raw_posix.c:811 +#5 0x0000aaaace3404b0 in bdrv_refresh_limits (bs=0xaaaad32ea920, errp=0xfffffef7a330, errp@entry=0xfffffef7a360) at block/io.c:122 +#6 0x0000aaaace340504 in bdrv_refresh_limits (bs=bs@entry=0xaaaad09ce800, errp=errp@entry=0xfffffef7a3b0) at block/io.c:97 +#7 0x0000aaaace2eb9f0 in bdrv_open_common (bs=bs@entry=0xaaaad09ce800, file=file@entry=0xaaaad0e89800, options=<optimized out>, errp=errp@entry=0xfffffef7a450) +at block.c:1194 +#8 0x0000aaaace2eedec in bdrv_open_inherit (filename=<optimized out>, filename@entry=0xaaaad25f92d0 "/dev/mapper/36384c4f100630193359db7a80000011d", +reference=reference@entry=0x0, options=<optimized out>, options@entry=0xaaaad3d0f4b0, flags=<optimized out>, flags@entry=128, parent=parent@entry=0x0, +child_role=child_role@entry=0x0, errp=errp@entry=0xfffffef7a710) at block.c:1895 +#9 0x0000aaaace2ef510 in bdrv_open (filename=filename@entry=0xaaaad25f92d0 "/dev/mapper/36384c4f100630193359db7a80000011d", reference=reference@entry=0x0, +options=options@entry=0xaaaad3d0f4b0, flags=flags@entry=128, errp=errp@entry=0xfffffef7a710) at block.c:1979 +#10 0x0000aaaace331ef0 in blk_new_open (filename=filename@entry=0xaaaad25f92d0 "/dev/mapper/36384c4f100630193359db7a80000011d", reference=reference@entry=0x0, +options=options@entry=0xaaaad3d0f4b0, flags=128, errp=errp@entry=0xfffffef7a710) at block/block_backend.c:213 +#11 0x0000aaaace0da1f4 in blockdev_init (file=file@entry=0xaaaad25f92d0 "/dev/mapper/36384c4f100630193359db7a80000011d", bs_opts=bs_opts@entry=0xaaaad3d0f4b0, +errp=errp@entry=0xfffffef7a710) at blockdev.c:603 +#12 0x0000aaaace0dc478 in drive_new (all_opts=all_opts@entry=0xaaaad4dc31d0, block_default_type=<optimized out>) at blockdev.c:1116 +#13 0x0000aaaace0e3ee0 in add_init_drive ( +optstr=optstr@entry=0xaaaad0872ec0 "file=/dev/mapper/36384c4f100630193359db7a80000011d,format=raw,if=none,id=drive-scsi0-0-0-3,cache=none,aio=native") +at device_hotplug.c:46 +#14 0x0000aaaace0e3f78 in hmp_drive_add (mon=0xfffffef7a810, qdict=0xaaaad0c8f000) at device_hotplug.c:67 +#15 0x0000aaaacdf7d688 in handle_hmp_command (mon=0xfffffef7a810, cmdline=<optimized out>) at /usr/src/debug/qemu-kvm-2.8.1/monitor.c:3199 +#16 0x0000aaaacdf7d778 in qmp_human_monitor_command ( +command_line=0xaaaacfc8e3c0 "drive_add dummy file=/dev/mapper/36384c4f100630193359db7a80000011d,format=raw,if=none,id=drive-scsi0-0-0-3,cache=none,aio=native", +has_cpu_index=false, cpu_index=0, errp=errp@entry=0xfffffef7a968) at /usr/src/debug/qemu-kvm-2.8.1/monitor.c:660 +#17 0x0000aaaace0fdb30 in qmp_marshal_human_monitor_command (args=<optimized out>, ret=0xfffffef7a9e0, errp=0xfffffef7a9d8) at qmp-marshal.c:2223 +#18 0x0000aaaace3b6ad0 in do_qmp_dispatch (request=<optimized out>, errp=0xfffffef7aa20, errp@entry=0xfffffef7aa40) at qapi/qmp_dispatch.c:115 +#19 0x0000aaaace3b6d58 in qmp_dispatch (request=<optimized out>) at qapi/qmp_dispatch.c:142 +#20 0x0000aaaacdf79398 in handle_qmp_command (parser=<optimized out>, tokens=<optimized out>) at /usr/src/debug/qemu-kvm-2.8.1/monitor.c:4010 +#21 0x0000aaaace3bd6c0 in json_message_process_token (lexer=0xaaaacf834c80, input=<optimized out>, type=JSON_RCURLY, x=214, y=274) at qobject/json_streamer.c:105 +#22 0x0000aaaace3f3d4c in json_lexer_feed_char (lexer=lexer@entry=0xaaaacf834c80, ch=<optimized out>, flush=flush@entry=false) at qobject/json_lexer.c:319 +#23 0x0000aaaace3f3e6c in json_lexer_feed (lexer=0xaaaacf834c80, buffer=<optimized out>, size=<optimized out>) at qobject/json_lexer.c:369 +#24 0x0000aaaacdf77c64 in monitor_qmp_read (opaque=<optimized out>, buf=<optimized out>, size=<optimized out>) at /usr/src/debug/qemu-kvm-2.8.1/monitor.c:4040 +#25 0x0000aaaace0eab18 in tcp_chr_read (chan=<optimized out>, cond=<optimized out>, opaque=0xaaaacf90b280) at qemu_char.c:3260 +#26 0x0000ffff9dadf200 in g_main_context_dispatch () from /lib64/libglib-2.0.so.0 +#27 0x0000aaaace3c4a00 in glib_pollfds_poll () at util/main_loop.c:230 +--Type <RET> for more, q to quit, c to continue without paging-- +#28 0x0000aaaace3c4a88 in os_host_main_loop_wait (timeout=<optimized out>) at util/main_loop.c:278 +#29 0x0000aaaace3c4bf0 in main_loop_wait (nonblocking=<optimized out>) at util/main_loop.c:534 +#30 0x0000aaaace0f5d08 in main_loop () at vl.c:2120 +#31 0x0000aaaacdf3a770 in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at vl.c:5017 + + +From the bt we can see, when do qmp sush as drive_add, qemu main thread locks the qemu_global_mutex and do pread in raw_probe_alignmen. Pread is a synchronous operation. If backend storage network has a large delay or IO pressure is too large, the pread operation will not return for a long time, which make vcpu thread can't acquire qemu_global_mutex for a long time and make the vcpu thread unable to be scheduled for a long time. So virtual machine cpu soft lockup happened. + + +I thank qemu main thread should not hold qemu_global_mutex for a long time when do qmp that involving IO synchronous operation sush pread , ioctl, etc. + +Do you have any solutions or good ideas about it? Thanks for your reply! \ No newline at end of file |