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Subject: Re: [PATCH RFC 0/7] add socket to netdev page frag recycling support
To:     Yunsheng Lin <linyunsheng@huawei.com>, davem@davemloft.net,
        kuba@kernel.org
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From:   David Ahern <dsahern@gmail.com>
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Date:   Wed, 18 Aug 2021 16:05:52 -0600
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On 8/17/21 9:32 PM, Yunsheng Lin wrote:
> This patchset adds the socket to netdev page frag recycling
> support based on the busy polling and page pool infrastructure.
> 
> The profermance improve from 30Gbit to 41Gbit for one thread iperf
> tcp flow, and the CPU usages decreases about 20% for four threads
> iperf flow with 100Gb line speed in IOMMU strict mode.
> 
> The profermance improve about 2.5% for one thread iperf tcp flow
> in IOMMU passthrough mode.
> 

Details about the test setup? cpu model, mtu, any other relevant changes
/ settings.

How does that performance improvement compare with using the Tx ZC API?
At 1500 MTU I see a CPU drop on the Tx side from 80% to 20% with the ZC
API and ~10% increase in throughput. Bumping the MTU to 3300 and
performance with the ZC API is 2x the current model with 1/2 the cpu.

Epyc 7502, ConnectX-6, IOMMU off.

In short, it seems like improving the Tx ZC API is the better path
forward than per-socket page pools.