From: Paolo Bonzini <pbonzini@redhat.com>
To: Mike Day <ncmike@ncultra.org>
Cc: Paul Mckenney <paulmck@linux.vnet.ibm.com>,
Mathew Desnoyers <mathieu.desnoyers@efficios.com>,
qemu-devel@nongnu.org, Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: [Qemu-devel] [RFC PATCH] Convert ram_list to RCU DQ V2
Date: Tue, 03 Sep 2013 16:09:51 +0200 [thread overview]
Message-ID: <5225EDAF.2010302@redhat.com> (raw)
In-Reply-To: <CAGaKXu34URY3eiuS-Wd92p0Guc5FyXcqWDhLGu-Y86iyo+1w4g@mail.gmail.com>
Il 03/09/2013 15:56, Mike Day ha scritto:
>> > + /* this implements a long-running RCU critical section.
>> > + * When rcu reclaims in the code start to become numerous
>> > + * it will be necessary to reduce the granularity of this critical
>> > + * section.
>> > + */
>>
>> Please add the same comment (and a rcu_read_lock/unlock pair replacing
>> the ramlist mutex) in ram_save_iterate, too.
>
> Just double checking on this particular change. In practice ram_save
> manipulates the ram_list indirectly through ram_save_block. But I'm
> assuming you want this change because of the ram state info that
> persists between calls to ram_save (ram_list version in particular).
ram_list.version is not really a problem, but last_seen_block has to
persist across ram_save_block calls.
> Also, there is potential for the callback functions
> ram_control_*_iterate to manipulate the ram_list.
I think that's right now not possible (and they could use
rcu_read_lock/unlock as well).
Paolo
next prev parent reply other threads:[~2013-09-03 14:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-30 16:06 [Qemu-devel] [RFC PATCH] Convert ram_list to RCU DQ V2 Mike Day
2013-08-30 16:38 ` Paolo Bonzini
2013-09-03 13:56 ` Mike Day
2013-09-03 14:09 ` Paolo Bonzini [this message]
2013-09-03 14:19 ` Mike Day
2013-09-03 14:21 ` Paolo Bonzini
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