From: Jason Wang <jasowang@redhat.com>
To: mst@redhat.com, kvm@vger.kernel.org,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: wexu@redhat.com, peterx@redhat.com, vkaplans@redhat.com,
maxime.coquelin@redhat.com
Subject: Re: [PATCH V2] vhost: introduce O(1) vq metadata cache
Date: Wed, 15 Feb 2017 13:37:17 +0800 [thread overview]
Message-ID: <ab222583-17ac-a4fb-0547-487caa8b866d@redhat.com> (raw)
In-Reply-To: <1481709237-19827-1-git-send-email-jasowang@redhat.com>
On 2016年12月14日 17:53, Jason Wang wrote:
> When device IOTLB is enabled, all address translations were stored in
> interval tree. O(lgN) searching time could be slow for virtqueue
> metadata (avail, used and descriptors) since they were accessed much
> often than other addresses. So this patch introduces an O(1) array
> which points to the interval tree nodes that store the translations of
> vq metadata. Those array were update during vq IOTLB prefetching and
> were reset during each invalidation and tlb update. Each time we want
> to access vq metadata, this small array were queried before interval
> tree. This would be sufficient for static mappings but not dynamic
> mappings, we could do optimizations on top.
>
> Test were done with l2fwd in guest (2M hugepage):
>
> noiommu | before | after
> tx 1.32Mpps | 1.06Mpps(82%) | 1.30Mpps(98%)
> rx 2.33Mpps | 1.46Mpps(63%) | 2.29Mpps(98%)
>
> We can almost reach the same performance as noiommu mode.
>
> Signed-off-by: Jason Wang<jasowang@redhat.com>
> ---
> Changes from V1:
> - silent 32bit build warning
ping
next prev parent reply other threads:[~2017-02-15 5:37 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-14 9:53 [PATCH V2] vhost: introduce O(1) vq metadata cache Jason Wang
2017-02-15 5:37 ` Jason Wang [this message]
2017-02-27 18:35 ` Michael S. Tsirkin
2017-02-28 3:23 ` Jason Wang
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