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Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with G
From: |
Christian Borntraeger |
Subject: |
Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable |
Date: |
Mon, 16 Nov 2015 09:16:09 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 |
On 11/16/2015 08:13 AM, Pavel Fedin wrote:
> Hello!
>
>>>> (process:4102): GLib-CRITICAL **: g_hash_table_iter_next: assertion
>>>> 'ri->version == ri->hash_table->version' failed
>>>>
>>>> (process:4102): GLib-CRITICAL **: g_hash_table_iter_next: assertion
>>>> 'ri->version == ri->hash_table->version' failed
>>>>
>>>> (process:4102): GLib-CRITICAL **: iter_remove_or_steal: assertion
>>>> 'ri->version == ri->hash_table->version' failed
>
> Wow... Actually this may come from attempts to modify the tree inside
> iteration.
>
>> Thanks! sclp_init() seems to violate several QOM design principles in
>> that it uses object_new() during TypeInfo::instance_init() and uses a
>> TYPE_... constant as property name. But nothing else stands out immediately.
>
> I think we should refactor this and retry. If not all problems go away, then
> we are indeed modifying the tree during iteration, and
> we have to find some solution.
David, Conny,
the current tree of afaerber
https://github.com/afaerber/qemu-cpu/commits/qom-next
has this patch:
> From: Pavel Fedin <address@hidden>
>
> ARM GICv3 systems with large number of CPUs create lots of IRQ pins. Since
> every pin is represented as a property, number of these properties becomes
> very large. Every property add first makes sure there's no duplicates.
> Traversing the list becomes very slow, therefore qemu initialization takes
> significant time (several seconds for e. g. 16 CPUs).
>
> This patch replaces list with GHashTable, making lookup very fast. The only
> drawback is that object_child_foreach() and object_child_foreach_recursive()
> cannot modify their objects during traversal, since GHashTableIter does not
> have modify-safe version. However, the code seems not to modify objects via
> these functions.
>
> Signed-off-by: Daniel P. Berrange <address@hidden>
> Signed-off-by: Pavel Fedin <address@hidden>
which causes failures in make check. A simple reproducer is
qemu-system-s390x -device sclp,help
any idea what would be the most simple fix?
Can we refactor this to create the event facility and the bus in the
machine or whatever?
> I wonder... Could we have both list and hashtable? hashtable for searching
> by name and list for iteration. In this case we would
> not have to use glib's iterators, and would be free of problems with them.
> Just keep the list and hashtable in sync.
> Or, is there any hashtable implementation out there which would keep
> iterators valid during modification?
> OTOH, glib has a function "remove the element at iterator's position", and
> we could postpone addition. So, perhaps, using both
> containers would be an overkill, just refactor the code to adapt to the new
> behavior.
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Andreas Färber, 2015/11/05
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Andreas Färber, 2015/11/13
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Christian Borntraeger, 2015/11/13
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Andreas Färber, 2015/11/13
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Pavel Fedin, 2015/11/16
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable,
Christian Borntraeger <=
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Andreas Färber, 2015/11/16
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Pavel Fedin, 2015/11/16
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Andreas Färber, 2015/11/16
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Daniel P. Berrange, 2015/11/16
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Paolo Bonzini, 2015/11/16
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Andreas Färber, 2015/11/16
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Paolo Bonzini, 2015/11/16
- Re: [Qemu-devel] [PATCH v4 6/7] qom: replace object property list with GHashTable, Daniel P. Berrange, 2015/11/16