linux-kernel - RE: [PATCH V2,net] net: mana: Fix perf regression: remove rx_cqes, tx

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Message-ID: <PH7PR21MB311639268988CD72DA545774CA47A@PH7PR21MB3116.namprd21.prod.outlook.com>
Date:   Fri, 26 May 2023 14:42:07 +0000
From:   Haiyang Zhang <haiyangz@...rosoft.com>
To:     Jakub Kicinski <kuba@...nel.org>
CC:     "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Dexuan Cui <decui@...rosoft.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Paul Rosswurm <paulros@...rosoft.com>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
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        Long Li <longli@...rosoft.com>,
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        Ajay Sharma <sharmaajay@...rosoft.com>,
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        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: RE: [PATCH V2,net] net: mana: Fix perf regression: remove rx_cqes,
 tx_cqes counters



> -----Original Message-----
> From: Jakub Kicinski <kuba@...nel.org>
> Sent: Thursday, May 25, 2023 11:26 PM
> To: Haiyang Zhang <haiyangz@...rosoft.com>
> Cc: linux-hyperv@...r.kernel.org; netdev@...r.kernel.org; Dexuan Cui
> <decui@...rosoft.com>; KY Srinivasan <kys@...rosoft.com>; Paul Rosswurm
> <paulros@...rosoft.com>; olaf@...fle.de; vkuznets@...hat.com;
> davem@...emloft.net; wei.liu@...nel.org; edumazet@...gle.com;
> pabeni@...hat.com; leon@...nel.org; Long Li <longli@...rosoft.com>;
> ssengar@...ux.microsoft.com; linux-rdma@...r.kernel.org;
> daniel@...earbox.net; john.fastabend@...il.com; bpf@...r.kernel.org;
> ast@...nel.org; Ajay Sharma <sharmaajay@...rosoft.com>;
> hawk@...nel.org; tglx@...utronix.de; shradhagupta@...ux.microsoft.com;
> linux-kernel@...r.kernel.org; stable@...r.kernel.org
> Subject: Re: [PATCH V2,net] net: mana: Fix perf regression: remove rx_cqes,
> tx_cqes counters
> 
> On Thu, 25 May 2023 07:46:30 -0700 Haiyang Zhang wrote:
> > lot caching and memory overhead, hence perf regression.
> 
> Horatiu's ask for more details was perfectly reasonable.
> Provide more details to give the distros and users an
> idea of the order of magnitude of the problem. Example
> workload and relative perf hit, anything.

For example, a workload is iperf with 128 threads, and with RPS enabled.
We saw perf regression of 25% with the previous patch adding the counters.
And this patch eliminates the regression. 

Thanks,
- Haiyang