From: Roland Dreier <rdreier@cisco.com>
To: David Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org, shemminger@linux-foundation.org,
jgarzik@pobox.com, hadi@cyberus.ca, rusty@rustcorp.com.au
Subject: Re: [PATCH RFC]: napi_struct V4
Date: Sat, 28 Jul 2007 08:27:18 -0700 [thread overview]
Message-ID: <ada1wesy2eh.fsf@cisco.com> (raw)
In-Reply-To: <20070725.013154.34764933.davem@davemloft.net> (David Miller's message of "Wed, 25 Jul 2007 01:31:54 -0700 (PDT)")
> Most drivers are in good shape, although some still have very
> questionable netif_rx_complete() handling, in that racy area that
> Rusty and myself were discussing today.
>
> My inclination is to wrap those sequences around with an IRQ
> safe spinlock to fix the race provably, and then if driver
> authors want to optimize that away with techniques like those
> that tg3, bnx2, sky2, skge et al. use, that's fine but can
> be done later.
Ouch... that extra lock seems pretty expensive. Also I'm having a
hard time understanding how the techniques you're alluding to apply to
devices that may miss events when enabling interrupts; the drivers you
mention all seem to be for devices that didn't have the race and
didn't use netif_rx_reschedule() in the old NAPI world. Can you
provide a little more detail on how the lock could be optimized away?
Thanks,
Roland
next prev parent reply other threads:[~2007-07-28 15:27 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-25 8:31 [PATCH RFC]: napi_struct V4 David Miller
2007-07-25 8:56 ` Stephen Hemminger
2007-07-26 0:37 ` David Miller
2007-07-26 1:55 ` Jeff Garzik
2007-07-26 1:56 ` David Miller
2007-07-26 2:00 ` Jeff Garzik
2007-07-26 2:02 ` David Miller
2007-07-28 18:08 ` Jeff Garzik
2007-07-29 5:33 ` David Miller
2007-07-25 12:01 ` jamal
2007-07-26 4:09 ` David Miller
2007-07-26 6:33 ` Michael Chan
2007-07-26 6:38 ` David Miller
2007-07-26 7:05 ` Michael Chan
2007-07-26 7:15 ` David Miller
2007-07-26 21:38 ` Michael Chan
2007-07-31 0:25 ` David Miller
2007-07-26 6:39 ` Michael Chan
2007-07-26 6:43 ` David Miller
2007-07-28 15:27 ` Roland Dreier [this message]
2007-07-29 5:32 ` David Miller
2007-07-30 15:04 ` Roland Dreier
2007-07-30 22:48 ` David Miller
2007-07-31 2:01 ` Roland Dreier
2007-07-31 2:03 ` David Miller
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