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From: David Miller <davem@davemloft.net>
To: rusty@rustcorp.com.au
Cc: netdev@vger.kernel.org, shemminger@linux-foundation.org,
	jgarzik@pobox.com
Subject: Re: [PATCH]: Resurrect napi_poll patch.
Date: Sat, 21 Jul 2007 18:59:05 -0700 (PDT)	[thread overview]
Message-ID: <20070721.185905.18310463.davem@davemloft.net> (raw)
In-Reply-To: <1185059423.6344.53.camel@localhost.localdomain>

From: Rusty Russell <rusty@rustcorp.com.au>
Date: Sun, 22 Jul 2007 09:10:23 +1000

> In five years' time, the "napi_struct for simple drivers" in net_device
> will look confusing.  Since your change touches all NAPI drivers anyway,
> it'd be nice to go straight to "everyone allocates their own NAPI
> struct" in one jump.

Good point.

But note that you'd be adding a pointer deref, the current sequence:

napi_struct --> netdev --> driver_private

involves all pointer arithmetic and no derefs, whereas:

napi_struct --> driver_private --> netdev

will involve at least on deref to get to the netdev from the
driver_private.

(Ignore the fact that netdev_priv() is not currently optimized
 as it used to be, that's an abberation of the current multi-queue
 implementation and will be fixed).

So this suggestion does have real downsides.

  reply	other threads:[~2007-07-22  1:59 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-07-21  5:31 [PATCH]: Resurrect napi_poll patch David Miller
2007-07-21  5:46 ` Patrick McHardy
2007-07-21  6:00   ` David Miller
2007-07-21  7:14 ` Rusty Russell
2007-07-21  7:42   ` David Miller
2007-07-21  8:00     ` Rusty Russell
2007-07-21 18:54       ` David Miller
2007-07-21 23:10         ` Rusty Russell
2007-07-22  1:59           ` David Miller [this message]
2007-07-22  2:39             ` Rusty Russell
2007-07-22  3:54               ` David Miller
2007-07-22  7:18                 ` David Miller
2007-07-22  7:36                   ` David Miller
2007-07-22  7:51                   ` Rusty Russell
2007-07-22  8:24                     ` David Miller
2007-07-21 13:26 ` Andi Kleen
2007-07-23  9:58   ` Stephen Hemminger
2007-07-23 17:06     ` Andi Kleen
2007-07-23 21:14       ` Stephen Hemminger

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