| Message ID | 1445339117-16278-1-git-send-email-dgilbert@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Tue, 10/20 12:05, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > Two new gdb commands are added: > > qemu iohandlers > > that dumps the list of waiting iohandlers, this is particularly > useful for trying to figure out where an incoming migration is > blocked. For 'fd_coroutine_enter' cases we dump a full backtrace. > > qemu aios > that dumps the qemu_aio_context list. I'd assume "qemu aios" is a command to print the list of AioContext instances rather than handlers in a particular context (qemu_aio_context). How about "qemu handlers"? > > This is a rewrite of an earlier version prior to Fam's changes > to the corresponding structures. > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > (gdb) qemu aios > ---- > {pfd = {fd = 12, events = 25, revents = 0}, io_read = 0x5634d4033cc0 > <qemu_laio_completion_cb>, io_write = 0x0, deleted = 0, opaque = > 0x5634d601e8b8, node = {le_next = 0x5634d5fd2330, le_prev = > 0x5634d5fd22a0}} > ---- > {pfd = {fd = 6, events = 25, revents = 0}, io_read = 0x5634d3ff1750 > <event_notifier_dummy_cb>, io_write = 0x0, deleted = 0, opaque = > 0x5634d5fd22e8, node = {le_next = 0x0, le_prev = 0x5634d5fe8458}} > ---- > > (gdb) qemu iohandlers > ---- > {pfd = {fd = 15, events = 25, revents = 0}, io_read = 0x559a843bd850 > <fd_coroutine_enter>, io_write = 0x0, deleted = 0, opaque = > 0x7fef1c5fed30, node = {le_next = 0x559a84e9d180, le_prev = > 0x559a84e9c6b0}} > #0 0x0000559a843bdcf0 in qemu_coroutine_switch > (from_=from_@entry=0x559a865fd8e0, to_=to_@entry=0x7fef37774ac8, > action=action@entry=COROUTINE_YIELD) at > /home/dgilbert/git/qemu-world3/coroutine-ucontext.c:177 > #1 0x0000559a843bd0d0 in qemu_coroutine_yield () at > /home/dgilbert/git/qemu-world3/qemu-coroutine.c:145 > #2 0x0000559a843bd9c5 in yield_until_fd_readable (fd=15) at > /home/dgilbert/git/qemu-world3/qemu-coroutine-io.c:90 > #3 0x0000559a84362337 in socket_get_buffer (opaque=0x559a862f7a00, > buf=0x559a84ea0a70 "", pos=<optimized out>, size=32768) at > /home/dgilbert/git/qemu-world3/migration/qemu-file-unix.c:69 > #4 0x0000559a84360c9c in qemu_fill_buffer (f=0x559a84ea0a40) > at /home/dgilbert/git/qemu-world3/migration/qemu-file.c:215 > #5 0x0000559a84361569 in qemu_peek_byte (f=0x559a84ea0a40, offset=0) > at /home/dgilbert/git/qemu-world3/migration/qemu-file.c:448 > #6 0x0000559a843617d4 in qemu_get_be32 (f=0x559a84ea0a40) > at /home/dgilbert/git/qemu-world3/migration/qemu-file.c:461 > #7 0x0000559a843617d4 in qemu_get_be32 (f=f@entry=0x559a84ea0a40) > at /home/dgilbert/git/qemu-world3/migration/qemu-file.c:545 > #8 0x0000559a84187d92 in qemu_loadvm_state (f=f@entry=0x559a84ea0a40) > at /home/dgilbert/git/qemu-world3/migration/savevm.c:1070 > #9 0x0000559a8435dc42 in process_incoming_migration_co > (opaque=0x559a84ea0a40) > at /home/dgilbert/git/qemu-world3/migration/migration.c:285 > #10 0x0000559a843bdd5a in coroutine_trampoline (i0=<optimized out>, > i1=<optimized out>) > at /home/dgilbert/git/qemu-world3/coroutine-ucontext.c:80 > #11 0x00007fef2a462f10 in __start_context () at /lib64/libc.so.6 > #12 0x00007fffb7437b50 in () > #13 0x0000000000000000 in () This sort of clutters the output, I'm wondering if making the backtrace optional (only dumped when "qemu iohandlers --backtrace") is better? It's OK if you decide to keep this, though. > ---- > {pfd = {fd = 4, events = 25, revents = 0}, io_read = 0x559a843b7800 > <sigfd_handler>, io_write = 0x0, deleted = 0, opaque = 0x4, node = > {le_next = 0x559a84e9c740, le_prev = 0x559a86325498}} > ---- > {pfd = {fd = 5, events = 25, revents = 0}, io_read = 0x559a843ac750 > <event_notifier_dummy_cb>, io_write = 0x0, deleted = 0, opaque = > 0x559a84e9c6f8, node = {le_next = 0x0, le_prev = 0x559a84e9d1a8}} > ---- > --- > scripts/qemu-gdb.py | 4 +++- > scripts/qemugdb/aio.py | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 55 insertions(+), 1 deletion(-) > create mode 100644 scripts/qemugdb/aio.py > > diff --git a/scripts/qemu-gdb.py b/scripts/qemu-gdb.py > index d6f2e5a..99344c7 100644 > --- a/scripts/qemu-gdb.py > +++ b/scripts/qemu-gdb.py > @@ -26,7 +26,7 @@ import os, sys > > sys.path.append(os.path.dirname(__file__)) > > -from qemugdb import mtree, coroutine > +from qemugdb import aio, mtree, coroutine > > class QemuCommand(gdb.Command): > '''Prefix for QEMU debug support commands''' > @@ -37,6 +37,8 @@ class QemuCommand(gdb.Command): > QemuCommand() > coroutine.CoroutineCommand() > mtree.MtreeCommand() > +aio.IOhandlersCommand() > +aio.AIOsCommand() > > # Default to silently passing through SIGUSR1, because QEMU sends it > # to itself a lot. > diff --git a/scripts/qemugdb/aio.py b/scripts/qemugdb/aio.py > new file mode 100644 > index 0000000..cda2c37 > --- /dev/null > +++ b/scripts/qemugdb/aio.py > @@ -0,0 +1,52 @@ > +#!/usr/bin/python > + > +# GDB debugging support: aio/iohandler debug > +# > +# Copyright (c) 2015 Red Hat, Inc. > +# > +# Author: Dr. David Alan Gilbert <dgilbert@redhat.com> > +# > +# This work is licensed under the terms of the GNU GPL, version 2 or > +# later. See the COPYING file in the top-level directory. > +# > + > +import gdb > +from qemugdb import coroutine > + > +def isnull(ptr): > + return ptr == gdb.Value(0).cast(ptr.type) > + > +def dump_aiocontext(context): > + '''Display a dump and backtrace for an aiocontext''' > + cur = context['aio_handlers']['lh_first'] > + # Get pointers to functions we're going to process specially > + sym_fd_coroutine_enter = gdb.parse_and_eval('fd_coroutine_enter') > + > + while not isnull(cur): > + entry = cur.dereference() > + gdb.write('----\n%s\n' % entry) > + if cur['io_read'] == sym_fd_coroutine_enter: > + coptr = (cur['opaque'].cast(gdb.lookup_type('FDYieldUntilData').pointer()))['co'] > + coptr = coptr.cast(gdb.lookup_type('CoroutineUContext').pointer()) > + coroutine.bt_jmpbuf(coptr['env']['__jmpbuf']) > + cur = cur['node']['le_next']; > + > + gdb.write('----\n') > + > +class AIOsCommand(gdb.Command): > + '''Display aio handlers''' Maybe also s/aio handlers/aio handlers in main loop/ ? > + def __init__(self): > + gdb.Command.__init__(self, 'qemu aios', gdb.COMMAND_DATA, > + gdb.COMPLETE_NONE) > + > + def invoke(self, arg, from_tty): > + dump_aiocontext(gdb.parse_and_eval('qemu_aio_context')) > + > +class IOhandlersCommand(gdb.Command): > + '''Display io handlers''' > + def __init__(self): > + gdb.Command.__init__(self, 'qemu iohandlers', gdb.COMMAND_DATA, > + gdb.COMPLETE_NONE) > + > + def invoke(self, arg, from_tty): > + dump_aiocontext(gdb.parse_and_eval('iohandler_ctx')) > -- > 2.5.0 >
On Fri, Oct 23, 2015 at 10:32 AM, Fam Zheng <famz@redhat.com> wrote: > On Tue, 10/20 12:05, Dr. David Alan Gilbert (git) wrote: >> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> >> >> Two new gdb commands are added: >> >> qemu iohandlers >> >> that dumps the list of waiting iohandlers, this is particularly >> useful for trying to figure out where an incoming migration is >> blocked. For 'fd_coroutine_enter' cases we dump a full backtrace. >> >> qemu aios >> that dumps the qemu_aio_context list. > > I'd assume "qemu aios" is a command to print the list of AioContext instances > rather than handlers in a particular context (qemu_aio_context). How about > "qemu handlers"? Seems fine to me but it would be useful to add an optional AioContext pointer argument. That way the command prints qemu_aio_context by default but can also be used to inspect arbitrary AioContexts. Stefan
On Fri, 10/23 11:09, Stefan Hajnoczi wrote: > On Fri, Oct 23, 2015 at 10:32 AM, Fam Zheng <famz@redhat.com> wrote: > > On Tue, 10/20 12:05, Dr. David Alan Gilbert (git) wrote: > >> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > >> > >> Two new gdb commands are added: > >> > >> qemu iohandlers > >> > >> that dumps the list of waiting iohandlers, this is particularly > >> useful for trying to figure out where an incoming migration is > >> blocked. For 'fd_coroutine_enter' cases we dump a full backtrace. > >> > >> qemu aios > >> that dumps the qemu_aio_context list. > > > > I'd assume "qemu aios" is a command to print the list of AioContext instances > > rather than handlers in a particular context (qemu_aio_context). How about > > "qemu handlers"? > > Seems fine to me but it would be useful to add an optional AioContext > pointer argument. > > That way the command prints qemu_aio_context by default but can also > be used to inspect arbitrary AioContexts. > That is a good idea. Fam
On 20/10/2015 13:05, Dr. David Alan Gilbert (git) wrote: > + entry = cur.dereference() > + gdb.write('----\n%s\n' % entry) > + if cur['io_read'] == sym_fd_coroutine_enter: > + coptr = (cur['opaque'].cast(gdb.lookup_type('FDYieldUntilData').pointer()))['co'] > + coptr = coptr.cast(gdb.lookup_type('CoroutineUContext').pointer()) > + coroutine.bt_jmpbuf(coptr['env']['__jmpbuf']) The last two lines here can be written as coroutine.bt_jmpbuf(coroutine.coroutine_to_jmpbuf(coptr)) with the head of Stefan's trace branch. Paolo
* Paolo Bonzini (pbonzini@redhat.com) wrote: > > > On 20/10/2015 13:05, Dr. David Alan Gilbert (git) wrote: > > + entry = cur.dereference() > > + gdb.write('----\n%s\n' % entry) > > + if cur['io_read'] == sym_fd_coroutine_enter: > > + coptr = (cur['opaque'].cast(gdb.lookup_type('FDYieldUntilData').pointer()))['co'] > > + coptr = coptr.cast(gdb.lookup_type('CoroutineUContext').pointer()) > > + coroutine.bt_jmpbuf(coptr['env']['__jmpbuf']) > > The last two lines here can be written as > > coroutine.bt_jmpbuf(coroutine.coroutine_to_jmpbuf(coptr)) > > with the head of Stefan's trace branch. I've just posted a new version with all the other changes in, but I can easily change that one when the trace change lands. Dave > > Paolo -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
diff --git a/scripts/qemu-gdb.py b/scripts/qemu-gdb.py index d6f2e5a..99344c7 100644 --- a/scripts/qemu-gdb.py +++ b/scripts/qemu-gdb.py @@ -26,7 +26,7 @@ import os, sys sys.path.append(os.path.dirname(__file__)) -from qemugdb import mtree, coroutine +from qemugdb import aio, mtree, coroutine class QemuCommand(gdb.Command): '''Prefix for QEMU debug support commands''' @@ -37,6 +37,8 @@ class QemuCommand(gdb.Command): QemuCommand() coroutine.CoroutineCommand() mtree.MtreeCommand() +aio.IOhandlersCommand() +aio.AIOsCommand() # Default to silently passing through SIGUSR1, because QEMU sends it # to itself a lot. diff --git a/scripts/qemugdb/aio.py b/scripts/qemugdb/aio.py new file mode 100644 index 0000000..cda2c37 --- /dev/null +++ b/scripts/qemugdb/aio.py @@ -0,0 +1,52 @@ +#!/usr/bin/python + +# GDB debugging support: aio/iohandler debug +# +# Copyright (c) 2015 Red Hat, Inc. +# +# Author: Dr. David Alan Gilbert <dgilbert@redhat.com> +# +# This work is licensed under the terms of the GNU GPL, version 2 or +# later. See the COPYING file in the top-level directory. +# + +import gdb +from qemugdb import coroutine + +def isnull(ptr): + return ptr == gdb.Value(0).cast(ptr.type) + +def dump_aiocontext(context): + '''Display a dump and backtrace for an aiocontext''' + cur = context['aio_handlers']['lh_first'] + # Get pointers to functions we're going to process specially + sym_fd_coroutine_enter = gdb.parse_and_eval('fd_coroutine_enter') + + while not isnull(cur): + entry = cur.dereference() + gdb.write('----\n%s\n' % entry) + if cur['io_read'] == sym_fd_coroutine_enter: + coptr = (cur['opaque'].cast(gdb.lookup_type('FDYieldUntilData').pointer()))['co'] + coptr = coptr.cast(gdb.lookup_type('CoroutineUContext').pointer()) + coroutine.bt_jmpbuf(coptr['env']['__jmpbuf']) + cur = cur['node']['le_next']; + + gdb.write('----\n') + +class AIOsCommand(gdb.Command): + '''Display aio handlers''' + def __init__(self): + gdb.Command.__init__(self, 'qemu aios', gdb.COMMAND_DATA, + gdb.COMPLETE_NONE) + + def invoke(self, arg, from_tty): + dump_aiocontext(gdb.parse_and_eval('qemu_aio_context')) + +class IOhandlersCommand(gdb.Command): + '''Display io handlers''' + def __init__(self): + gdb.Command.__init__(self, 'qemu iohandlers', gdb.COMMAND_DATA, + gdb.COMPLETE_NONE) + + def invoke(self, arg, from_tty): + dump_aiocontext(gdb.parse_and_eval('iohandler_ctx'))