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Re: [Qemu-devel] [PATCH] gdb command: qemu iohandlers
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH] gdb command: qemu iohandlers |
Date: |
Wed, 24 Jun 2015 16:19:51 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Tue, Jun 23, 2015 at 03:43:53PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> Add a gdb command to print the current set of IOHandlers and
> if one of them is a thread yielding for data print the backtrace.
>
> Useful for debugging why an incoming migration has stalled, e.g.
>
> ----
> {fd_read = 0x7fd4c8e40d00 <fd_coroutine_enter>, fd_write = 0x0, opaque =
> 0x7fd4b8bfeb00, next = {le_next = 0x7fd4cac81b00, le_prev =
> 0x7fd4c93d2bd0 <io_handlers>}, fd = 22, pollfds_idx = 0, deleted =
> false}
> #0 qemu_coroutine_switch (address@hidden,
> address@hidden,
> address@hidden) at coroutine-ucontext.c:177
> #1 0x00007fd4c8e40507 in qemu_coroutine_yield () at
> qemu-coroutine.c:145
> #2 0x00007fd4c8e40e75 in yield_until_fd_readable (fd=22) at
> qemu-coroutine-io.c:90
> #3 0x00007fd4c8df347f in qemu_rdma_block_for_wrid
> (address@hidden,
> address@hidden,
> address@hidden) at migration/rdma.c:1510
> #4 0x00007fd4c8df388f in qemu_rdma_post_send_control
> (address@hidden, address@hidden,
> address@hidden) at migration/rdma.c:1608
> #5 0x00007fd4c8df4b8e in qemu_rdma_exchange_recv (rdma=0x7fd4b8c7e010,
> head=0x7fd4b8bfed50, expecting=3)
> at migration/rdma.c:1814
> #6 0x00007fd4c8df5089 in qemu_rdma_get_buffer (opaque=0x7fd4cba34950,
> buf=0x7fd4cc24fd20 "TR\022",
> pos=<optimized out>, size=32768) at migration/rdma.c:2611
> #7 0x00007fd4c8df000d in qemu_fill_buffer (address@hidden) at
> migration/qemu-file.c:214
> #8 0x00007fd4c8df08d4 in qemu_peek_byte (address@hidden,
> address@hidden)
> at migration/qemu-file.c:447
> #9 0x00007fd4c8c2cad1 in qemu_loadvm_state (address@hidden)
> at /root/qemu-world3/migration/savevm.c:1128
> #10 0x00007fd4c8ded895 in process_incoming_migration_co
> (opaque=0x7fd4cc24fcf0) at migration/migration.c:145
> #11 0x00007fd4c8e4112a in coroutine_trampoline (i0=<optimized out>,
> i1=<optimized out>) at coroutine-ucontext.c:80
> #12 0x00007fd4c453e0f0 in ?? () from /lib64/libc.so.6
> #13 0x00007ffee263e870 in ?? ()
> #14 0x0000000000000000 in ?? ()
> ----
> {fd_read = 0x7fd4c8e3ace0 <sigfd_handler>, fd_write = 0x0, opaque = 0x5,
> next = {le_next = 0x0, le_prev = 0x7fd4cb78a3d8}, fd = 5, pollfds_idx =
> 1, deleted = false}
>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> ---
> scripts/qemu-gdb.py | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/scripts/qemu-gdb.py b/scripts/qemu-gdb.py
> index 6c7f4fb..2670625 100644
> --- a/scripts/qemu-gdb.py
> +++ b/scripts/qemu-gdb.py
> @@ -102,6 +102,30 @@ class CoroutineCommand(gdb.Command):
> coroutine_pointer =
> gdb.parse_and_eval(argv[0]).cast(gdb.lookup_type('CoroutineUContext').pointer())
> bt_jmpbuf(coroutine_pointer['env']['__jmpbuf'])
>
> +class IOhandlersCommand(gdb.Command):
> + '''Display a backtrace for io handlers'''
> + def __init__(self):
> + gdb.Command.__init__(self, 'qemu iohandlers', gdb.COMMAND_DATA,
> + gdb.COMPLETE_NONE)
> +
> + def invoke(self, arg, from_tty):
> + cur = gdb.parse_and_eval('io_handlers.lh_first')
Fam is getting rid of io_handlers and replacing it with an AioContext.
I have CCed him.
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