From: Joe Perches <joe@perches•com>
To: Zhang Shengju <zhangshengju@cmss•chinamobile.com>,
sathya.perla@broadcom•com, ajit.khaparde@broadcom•com,
sriharsha.basavapatna@broadcom•com, netdev@vger•kernel.org
Subject: Re: [net-next] be2net: use shift instead of expensive divide
Date: Mon, 28 Aug 2017 20:44:02 -0700 [thread overview]
Message-ID: <1503978242.2040.16.camel@perches.com> (raw)
In-Reply-To: <1503976719-3063-1-git-send-email-zhangshengju@cmss.chinamobile.com>
On Tue, 2017-08-29 at 11:18 +0800, Zhang Shengju wrote:
> Replace shift instead of expensive divide.
This change is mostly pointless.
Any half-way decent compiler should produce the same object.
gcc emits the same object with the old code.
The AMAP_GET_BITS macro uses the "offsetof(struct, member) / 32"
style too.
> diff --git a/drivers/net/ethernet/emulex/benet/be_main.c b/drivers/net/ethernet/emulex/benet/be_main.c
[]
> @@ -2455,7 +2455,7 @@ static struct be_rx_compl_info *be_rx_compl_get(struct be_rx_obj *rxo)
>
> /* For checking the valid bit it is Ok to use either definition as the
> * valid bit is at the same position in both v0 and v1 Rx compl */
> - if (compl->dw[offsetof(struct amap_eth_rx_compl_v1, valid) / 32] == 0)
> + if (compl->dw[offsetof(struct amap_eth_rx_compl_v1, valid) >> 5] == 0)
etc...
next prev parent reply other threads:[~2017-08-29 3:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-29 3:18 [net-next] be2net: use shift instead of expensive divide Zhang Shengju
2017-08-29 3:44 ` Joe Perches [this message]
2017-08-29 4:25 ` David Miller
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