netdev - Re: [PATCH 2/3] net-next/hinic:performance improvement for HiNIC

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Date:   Sat, 17 Nov 2018 12:22:12 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     xuechaojing@...wei.com
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        wulike1@...wei.com, chiqijun@...wei.com, fy.wang@...wei.com,
        tony.qu@...wei.com, luoshaokai@...wei.com
Subject: Re: [PATCH 2/3] net-next/hinic:performance improvement for HiNIC

From: Xue Chaojing <xuechaojing@...wei.com>
Date: Thu, 15 Nov 2018 20:05:47 +0000

> In order to improve performance, this patch adds rx checksum offload
> for the HiNIC driver and optimizes the code. Performance test(Iperf) 
> shows more than 95% improvement in TCP streams.
> 
> Signed-off-by: Xue Chaojing <xuechaojing@...wei.com>

What kind of "optimizes the code" is being done here?  Be explicit.

And such unrelated changes to supporting checksum offload should be
split into another patch.

> +	csum_err = HINIC_RQ_CQE_STATUS_GET(status, CSUM_ERR);
> +
> +	if (!(netdev->features & NETIF_F_RXCSUM))
> +		return;
> +
> +	if (!csum_err)
> +		skb->ip_summed = CHECKSUM_UNNECESSARY;
> +	else
> +		skb->ip_summed = CHECKSUM_NONE;

Does the CQE status word provide more information?  Like the checksum
computed over the packet?  That's more useful than a binary "csum correct"
state.

> +#define BIT(nr)			(1UL << (nr))

This is unnecessary, please include linux/bits.h and use the definition from
there.