From: Paolo Bonzini <pbonzini@redhat.com>
To: Harsh Bora <harsh@linux.vnet.ibm.com>
Cc: qemu-devel@nongnu.org, aneesh.kumar@linux.vnet.ibm.com
Subject: Re: [Qemu-devel] [PATCH 2/2] 9p-synth: use mutex on read-side
Date: Sat, 18 Aug 2012 20:46:47 +0200 [thread overview]
Message-ID: <502FE317.3020607@redhat.com> (raw)
In-Reply-To: <502951BC.1090400@linux.vnet.ibm.com>
Il 13/08/2012 21:13, Harsh Bora ha scritto:
>>
>
> Hi Paolo,
>
> The rcu_read_[un]lock() macros were added as no-ops (based on your
> inputs on #qemu) to replace reader-writer locks with RCU based locking
> as suggested while proposing QemuRWLock API for RW locks (See
> http://lists.gnu.org/archive/html/qemu-devel/2011-10/msg00192.html).
The rwlock was also premature optimization IMHO.
> v9fs_synth_mutex was actually a pthread_rwlock_t earlier.
> I am not sure if reader lock would be better than having a plain mutex
> for readers as well.
>
> Aneesh, inputs ?
>
> Also, if we are going forward with this change, we may also want to
> remove definition of QLIST_INSERT_HEAD_RCU, since the code being remove
> below is the only consumer of that macro.
It's in a library file, so I don't mind leaving it in. I think liu ping
fan's patches were using it.
Paolo
prev parent reply other threads:[~2012-08-18 18:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-08 11:55 [Qemu-devel] [PATCH 0/2] 9p-synth: remove poor-man RCU Paolo Bonzini
2012-08-08 11:55 ` [Qemu-devel] [PATCH 1/2] 9p-synth: fix read-side critical sections Paolo Bonzini
2012-08-13 18:47 ` Harsh Bora
2012-08-08 11:55 ` [Qemu-devel] [PATCH 2/2] 9p-synth: use mutex on read-side Paolo Bonzini
2012-08-13 19:13 ` Harsh Bora
2012-08-18 18:46 ` Paolo Bonzini [this message]
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