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Re: [Qemu-devel] [PATCH v3 2/3] scripts: add render_block_graph function
From: |
Eduardo Habkost |
Subject: |
Re: [Qemu-devel] [PATCH v3 2/3] scripts: add render_block_graph function for QEMUMachine |
Date: |
Thu, 23 Aug 2018 14:56:17 -0300 |
User-agent: |
Mutt/1.9.2 (2017-12-15) |
On Thu, Aug 23, 2018 at 06:46:54PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> Render block nodes graph with help of graphviz. This new function is
> for debugging, so there is no sense to put it into qemu.py as a method
> of QEMUMachine. Let's instead put it separately.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---
> scripts/render_block_graph.py | 120 ++++++++++++++++++++++++++++++++++
> 1 file changed, 120 insertions(+)
> create mode 100755 scripts/render_block_graph.py
>
> diff --git a/scripts/render_block_graph.py b/scripts/render_block_graph.py
> new file mode 100755
> index 0000000000..382cc769ef
> --- /dev/null
> +++ b/scripts/render_block_graph.py
> @@ -0,0 +1,120 @@
> +#!/usr/bin/env python
> +#
> +# Render Qemu Block Graph
> +#
> +# Copyright (c) 2018 Virtuozzo International GmbH. All rights reserved.
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 2 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program. If not, see <http://www.gnu.org/licenses/>.
> +#
> +
> +import os
> +import sys
> +import subprocess
> +import json
> +from graphviz import Digraph
> +from qemu import MonitorResponseError
> +
> +
> +def perm(arr):
> + s = 'w' if 'write' in arr else '_'
> + s += 'r' if 'consistent-read' in arr else '_'
> + s += 'u' if 'write-unchanged' in arr else '_'
> + s += 'g' if 'graph-mod' in arr else '_'
> + s += 's' if 'resize' in arr else '_'
> + return s
> +
> +
> +def render_block_graph(qmp, filename, format='png'):
> + '''
> + Render graph in text (dot) representation into "@filename" and
> + representation in @format into "@address@hidden"
> + '''
> +
> + bds_nodes = qmp.command('query-named-block-nodes')
> + bds_nodes = {n['node-name']: n for n in bds_nodes}
> +
> + job_nodes = qmp.command('query-block-jobs')
> + job_nodes = {n['device']: n for n in job_nodes}
> +
> + block_graph = qmp.command('x-debug-query-block-graph')
> +
> + graph = Digraph(comment='Block Nodes Graph')
> + graph.format = format
> + graph.node('permission symbols:\l'
> + ' w - Write\l'
> + ' r - consistent-Read\l'
> + ' u - write - Unchanged\l'
> + ' g - Graph-mod\l'
> + ' s - reSize\l'
> + 'edge label scheme:\l'
> + ' <child type>\l'
> + ' <perm>\l'
> + ' <shared_perm>\l', shape='none')
> +
> + for n in block_graph['nodes']:
> + if n['type'] == 'bds':
> + info = bds_nodes[n['name']]
> + label = n['name'] + ' [' + info['drv'] + ']'
> + if info['drv'] == 'file':
> + label += '\n' + os.path.basename(info['file'])
> + shape = 'ellipse'
> + elif n['type'] == 'job':
> + info = job_nodes[n['name']]
> + label = info['type'] + ' job (' + n['name'] + ')'
> + shape = 'box'
> + else:
> + assert n['type'] == 'blk'
> + label = n['name'] if n['name'] else 'unnamed blk'
> + shape = 'box'
> +
> + graph.node(str(n['id']), label, shape=shape)
> +
> + for e in block_graph['edges']:
> + label = '%s\l%s\l%s\l' % (e['name'], perm(e['perm']),
> + perm(e['shared-perm']))
> + graph.edge(str(e['parent']), str(e['child']), label=label)
> +
> + graph.render(filename)
> +
> +
> +class LibvirtGuest():
> + def __init__(self, name):
> + self.name = name
> +
> + def command(self, cmd):
> + # only supports qmp commands without parameters
> + m = {'execute': cmd}
> + ar = ['virsh', 'qemu-monitor-command', self.name, json.dumps(m)]
> +
> + reply = json.loads(subprocess.check_output(ar))
> +
> + if 'error' in reply:
> + raise MonitorResponseError(reply)
> +
> + return reply['return']
Interesting trick. :)
Suggestion for a follow-up patch: we could move this helper class
to qmp.py, so other scripts could use it too.
> +
> +
> +if __name__ == '__main__':
> + obj = sys.argv[1]
> + out = sys.argv[2]
> +
> + if os.path.exists(obj):
> + # assume unix socket
> + qmp = QEMUMonitorProtocol(obj)
> + qmp.connect()
> + else:
> + # assume libvirt guest name
> + qmp = LibvirtGuest(obj)
> +
> + render_block_graph(qmp, out)
> --
> 2.18.0
>
--
Eduardo