From: Paolo Bonzini <pbonzini@redhat.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Gleb Natapov <gleb@minantech.com>, KVM <kvm@vger.kernel.org>,
linux-s390 <linux-s390@vger.kernel.org>,
Cornelia Huck <cornelia.huck@de.ibm.com>,
Jens Freimann <jfrei@linux.vnet.ibm.com>,
agraf@suse.de, mst@redhat.com
Subject: Re: [PATCHv2/RFC] kvm/irqchip: Speed up KVM_SET_GSI_ROUTING
Date: Thu, 16 Jan 2014 13:59:14 +0100 [thread overview]
Message-ID: <52D7D7A2.2080409@redhat.com> (raw)
In-Reply-To: <1389876260-46636-1-git-send-email-borntraeger@de.ibm.com>
Il 16/01/2014 13:44, Christian Borntraeger ha scritto:
> I converted most of the rcu routines to srcu. Review for the unconverted
> use of hlist_for_each_entry_rcu, hlist_add_head_rcu, hlist_del_init_rcu
> is necessary, though. They look fine to me since they are protected by
> outer functions.
They are fine because they do not have lockdep checks
(hlist_for_each_entry_rcu uses rcu_dereference_raw rather than
rcu_dereference, and write-sides do not do rcu lockdep at all).
> In addition, we should also discuss if a global srcu (for all guests) is
> fine.
I think it is. It is already way cheaper than it used to be, and we're
hardly relying on the "sleepable" part of srcu. We just want its faster
detection of grace periods. One instance should be fine because our
read sides are so small and mostly they are not even preemptable.
Thanks for writing the patch!
Paolo
next prev parent reply other threads:[~2014-01-16 12:59 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-16 9:23 [PATCH] kvm/irqchip: Speed up KVM_SET_GSI_ROUTING Christian Borntraeger
2014-01-16 11:24 ` Paolo Bonzini
2014-01-16 12:44 ` [PATCHv2/RFC] " Christian Borntraeger
2014-01-16 12:59 ` Paolo Bonzini [this message]
2014-01-16 13:06 ` Christian Borntraeger
2014-01-16 13:07 ` Paolo Bonzini
2014-01-16 18:56 ` Michael S. Tsirkin
2014-01-17 8:29 ` Christian Borntraeger
2014-01-17 9:19 ` Paolo Bonzini
2014-02-19 22:23 ` Paolo Bonzini
2014-02-21 4:59 ` Andrew Theurer
2014-01-16 18:55 ` Michael S. Tsirkin
2014-01-16 20:07 ` [PATCHv3] " Christian Borntraeger
2014-01-16 20:22 ` Michael S. Tsirkin
2014-01-17 14:03 ` Paolo Bonzini
2014-01-17 15:03 ` Christian Borntraeger
2014-01-17 15:26 ` Paolo Bonzini
2014-02-21 17:35 ` [PATCHv2/RFC] " Paolo Bonzini
2014-02-24 11:58 ` [PATCHv2] " Christian Borntraeger
2014-02-24 12:02 ` Paolo Bonzini
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