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From: Peter Xu <peterx@redhat.com>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	qemu-devel@nongnu.org, "Michael S . Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH RFC 3/9] memory: Introduce log_sync_global() to memory listener
Date: Wed, 25 Mar 2020 13:02:56 -0400
Message-ID: <20200325170256.GG354390@xz-x1> (raw)
In-Reply-To: <20200325165252.GB2635@work-vm>

On Wed, Mar 25, 2020 at 04:52:52PM +0000, Dr. David Alan Gilbert wrote:
> * Peter Xu (peterx@redhat.com) wrote:
> > Some of the memory listener may want to do log synchronization without
> > being able to specify a range of memory to sync but always globally.
> > Such a memory listener should provide this new method instead of the
> > log_sync() method.
> > 
> > Obviously we can also achieve similar thing when we put the global
> > sync logic into a log_sync() handler. However that's not efficient
> > enough because otherwise memory_global_dirty_log_sync() may do the
> > global sync N times, where N is the number of flat views.
> > 
> > Make this new method be exclusive to log_sync().
> > 
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> 
> OK, so I guess the idea here is that when you have a ring with dirty
> pages on it, you just need to clear all outstanding things on the ring
> whereever they came from.

Yeah, or say it's about granularity of log_sync(), and the ring layout
will only be able to sync in a global manner rather than per-memslot.
It's actually not good when we only want to sync some specific small
memory region (e.g., the VGA code wants to only sync the VGA ram), but
we don't have much choice...

> 
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Thanks!

-- 
Peter Xu



  reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-05 14:17 [PATCH RFC 0/9] KVM: Dirty ring support (QEMU part) Peter Xu
2020-02-05 14:17 ` [PATCH RFC 1/9] KVM: Fixup kvm_log_clear_one_slot() ioctl return check Peter Xu
2020-03-25 16:34   ` Dr. David Alan Gilbert
2020-03-25 17:43   ` Peter Xu
2020-02-05 14:17 ` [PATCH RFC 2/9] linux-headers: Update Peter Xu
2020-02-05 14:17 ` [PATCH RFC 3/9] memory: Introduce log_sync_global() to memory listener Peter Xu
2020-03-25 16:52   ` Dr. David Alan Gilbert
2020-03-25 17:02     ` Peter Xu [this message]
2020-02-05 14:17 ` [PATCH RFC 4/9] KVM: Create the KVMSlot dirty bitmap on flag changes Peter Xu
2020-03-25 17:44   ` Dr. David Alan Gilbert
2020-02-05 14:17 ` [PATCH RFC 5/9] KVM: Provide helper to get kvm dirty log Peter Xu
2020-03-25 17:52   ` Dr. David Alan Gilbert
2020-03-25 18:15     ` Peter Xu
2020-02-05 14:17 ` [PATCH RFC 6/9] KVM: Provide helper to sync dirty bitmap from slot to ramblock Peter Xu
2020-03-25 18:47   ` Dr. David Alan Gilbert
2020-02-05 14:17 ` [PATCH RFC 7/9] KVM: Cache kvm slot dirty bitmap size Peter Xu
2020-03-25 18:49   ` Dr. David Alan Gilbert
2020-02-05 14:17 ` [PATCH RFC 8/9] KVM: Add dirty-ring-size property Peter Xu
2020-03-25 20:00   ` Dr. David Alan Gilbert
2020-03-25 20:42     ` Peter Xu
2020-03-26 13:41       ` Dr. David Alan Gilbert
2020-03-26 16:03         ` Peter Xu
2020-03-25 20:14   ` Dr. David Alan Gilbert
2020-03-25 20:48     ` Peter Xu
2020-02-05 14:17 ` [PATCH RFC 9/9] KVM: Dirty ring support Peter Xu
2020-03-25 20:41   ` Dr. David Alan Gilbert
2020-03-25 21:32     ` Peter Xu
2020-03-26 14:14       ` Dr. David Alan Gilbert
2020-03-26 16:10         ` Peter Xu
2020-02-05 14:51 ` [PATCH RFC 0/9] KVM: Dirty ring support (QEMU part) no-reply
2020-03-03 17:32 ` Peter Xu

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