Message-ID: <54E375B2.8090101@redhat.com>
Date: Tue, 17 Feb 2015 18:09:06 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
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To: Igor Mammedov <imammedo@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>
CC: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH] vhost: support upto 509 memory regions
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On 17/02/2015 16:02, Igor Mammedov wrote:
>> > 
>> > Not if there are about 6 regions, I think.
> When memslots where increased to 509 and look up of them was replaced on
> binary search results were on par with linear search for a default 13 memslots VM.
> 
> Adding LRU

You mean MRU. :)

> cache helped to shave ~40% of cycles for sequential lookup workloads.

It's a bit different for vhost because you can have up to four "things"
being looked up at the same time:

- the s/g list that will end up in the skb

- the avail/used ring

- the virtio buffers

- the virtio indirect buffers

So you probably need multiple MRU caches.  But yes, MRU can help a lot.

Paolo
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