From: Avi Kivity <avi@redhat.com>
To: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Cc: Peter Zijlstra <peterz@infradead.org>,
paulmck@linux.vnet.ibm.com, Oleg Nesterov <oleg@redhat.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Marcelo Tosatti <mtosatti@redhat.com>,
KVM list <kvm@vger.kernel.org>
Subject: Re: [RFC][PATCH] srcu: Implement call_srcu()
Date: Wed, 01 Feb 2012 15:24:36 +0200 [thread overview]
Message-ID: <4F293D14.5030008@redhat.com> (raw)
In-Reply-To: <4F291E1F.3030505@oss.ntt.co.jp>
On 02/01/2012 01:12 PM, Takuya Yoshikawa wrote:
> (2012/02/01 20:01), Avi Kivity wrote:
>> On 02/01/2012 01:00 PM, Takuya Yoshikawa wrote:
>
>>> How about just doing:
>>>
>>> take a spin_lock
>>> copy the entire (or some portions of) bitmap locally
>>> clear the bitmap
>>> unlock
>>>
>>
>> That means that vcpus dirtying memory also have to take that lock, and
>> spin while the bitmap is being copied. So kvm_vm_ioctl_get_dirty_log()
>> will become faster, at the expense of vcpus, which I think is a bad
>> tradeoff.
>
> Almost every caller is already holding the mmu_lock.
True. But let's not add more locks.
>
> Isn't it possible to make others hold the lock only for the case of
> marking to the bitmap? (I will check myself too.)
Yes, in walk_addr(), while setting accessed and dirty bits in guest
PTEs, or while emulating instructions and writing to guest memory.
>> That'll be great, numbers are better than speculation.
>>
>
>
> Yes, I already have some good numbers to show (and some patches).
Looking forward.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2012-02-01 13:24 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-31 13:32 [RFC][PATCH] srcu: Implement call_srcu() Peter Zijlstra
2012-01-31 13:47 ` Avi Kivity
2012-01-31 13:50 ` Peter Zijlstra
2012-01-31 22:24 ` Paul E. McKenney
2012-02-01 10:22 ` Peter Zijlstra
2012-02-01 10:44 ` Avi Kivity
2012-02-01 10:49 ` Avi Kivity
2012-02-01 11:00 ` Takuya Yoshikawa
2012-02-01 11:01 ` Avi Kivity
2012-02-01 11:12 ` Takuya Yoshikawa
2012-02-01 13:24 ` Avi Kivity [this message]
2012-02-02 5:46 ` [test result] dirty logging without srcu update -- " Takuya Yoshikawa
2012-02-02 10:10 ` Avi Kivity
2012-02-02 10:21 ` Takuya Yoshikawa
2012-02-02 10:21 ` Avi Kivity
2012-02-02 10:40 ` Takuya Yoshikawa
2012-02-02 11:02 ` Avi Kivity
2012-02-02 14:44 ` Takuya Yoshikawa
2012-02-02 14:57 ` Avi Kivity
2012-02-01 13:43 ` Marcelo Tosatti
2012-02-01 15:42 ` Takuya Yoshikawa
2012-02-01 13:50 ` Marcelo Tosatti
2012-02-01 14:07 ` Paul E. McKenney
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