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Subject: Re: [RFC PATCH V2 0/5] vhost: accelerate metadata access through
 vmap()
To:     Christoph Hellwig <hch@infradead.org>
Cc:     mst@redhat.com, kvm@vger.kernel.org,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
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References: <1551856692-3384-1-git-send-email-jasowang@redhat.com>
 <20190308141220.GA21082@infradead.org>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <56374231-7ba7-0227-8d6d-4d968d71b4d6@redhat.com>
Date:   Mon, 11 Mar 2019 15:13:17 +0800
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On 2019/3/8 下午10:12, Christoph Hellwig wrote:
> On Wed, Mar 06, 2019 at 02:18:07AM -0500, Jason Wang wrote:
>> This series tries to access virtqueue metadata through kernel virtual
>> address instead of copy_user() friends since they had too much
>> overheads like checks, spec barriers or even hardware feature
>> toggling. This is done through setup kernel address through vmap() and
>> resigter MMU notifier for invalidation.
>>
>> Test shows about 24% improvement on TX PPS. TCP_STREAM doesn't see
>> obvious improvement.
> How is this going to work for CPUs with virtually tagged caches?


Anything different that you worry? I can have a test but do you know any 
archs that use virtual tag cache?

Thanks