linux-kernel - Re: [RFC PATCH V2 1/2] vhost: convert pre sorted vhost memory array to interval tree

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Message-ID: <5721ABB0.8070509@redhat.com>
Date:	Thu, 28 Apr 2016 14:20:32 +0800
From:	Jason Wang <jasowang@...hat.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	peterx@...hat.com, pbonzini@...hat.com, qemu-devel@...gnu.org
Subject: Re: [RFC PATCH V2 1/2] vhost: convert pre sorted vhost memory array
 to interval tree



On 04/27/2016 07:30 PM, Michael S. Tsirkin wrote:
> On Fri, Mar 25, 2016 at 10:34:33AM +0800, Jason Wang wrote:
>> > Current pre-sorted memory region array has some limitations for future
>> > device IOTLB conversion:
>> > 
>> > 1) need extra work for adding and removing a single region, and it's
>> >    expected to be slow because of sorting or memory re-allocation.
>> > 2) need extra work of removing a large range which may intersect
>> >    several regions with different size.
>> > 3) need trick for a replacement policy like LRU
>> > 
>> > To overcome the above shortcomings, this patch convert it to interval
>> > tree which can easily address the above issue with almost no extra
>> > work.
>> > 
>> > The patch could be used for:
>> > 
>> > - Extend the current API and only let the userspace to send diffs of
>> >   memory table.
>> > - Simplify Device IOTLB implementation.
> Does this affect performance at all?
>

In pktgen test, no difference.

Thanks