From: Stephen Hemminger <shemminger@vyatta•com>
To: "Dimitrios Michailidis" <dm@chelsio•com>
Cc: <netdev@vger•kernel.org>
Subject: Re: [PATCH 4/7] cxgb4: Add packet queues and packet DMA code
Date: Fri, 26 Feb 2010 16:16:03 -0800 [thread overview]
Message-ID: <20100226161603.21975b6d@nehalam> (raw)
In-Reply-To: <8A71B368A89016469F72CD08050AD33401359B69@maui.asicdesigners.com>
On Fri, 26 Feb 2010 16:10:07 -0800
"Dimitrios Michailidis" <dm@chelsio•com> wrote:
>
>
> > -----Original Message-----
> > From: Stephen Hemminger [mailto:shemminger@vyatta•com]
> > Sent: Friday, February 26, 2010 3:58 PM
> > To: Dimitrios Michailidis
> > Cc: netdev@vger•kernel.org
> > Subject: Re: [PATCH 4/7] cxgb4: Add packet queues and packet DMA code
> >
> > On Fri, 26 Feb 2010 15:35:36 -0800
> > Dimitris Michailidis <dm@chelsio•com> wrote:
> >
> > > +
> > > +/**
> > > + * need_skb_unmap - does the platform need unmapping of sk_buffs?
> > > + *
> > > + * Returns true if the platfrom needs sk_buff unmapping. The
> compiler
> > > + * optimizes away unecessary code if this returns true.
> > > + */
> > > +static inline int need_skb_unmap(void)
> > > +{
> > > + /*
> > > + * This structure is used to tell if the platfrom needs buffer
> > > + * unmapping by checking if DECLARE_PCI_UNMAP_ADDR defines
> anything.
> > > + */
> > > + struct dummy {
> > > + DECLARE_PCI_UNMAP_ADDR(addr);
> > > + };
> > > +
> > > + return sizeof(struct dummy) != 0;
> > > +}
> > > +
> >
> > I would prefer one code path and let the compiler decide if unmap
> > should be nop; rather than this kind of trick code.
>
> I believe this function does not generate any code, the compiler
> statically figures out the result and optimizes any conditionals that
> call it. What option do you have in mind that would tell the compiler
> if unmap is nop?
Why do you care, let compiler decide.
--
next prev parent reply other threads:[~2010-02-27 0:16 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-27 0:10 [PATCH 4/7] cxgb4: Add packet queues and packet DMA code Dimitrios Michailidis
2010-02-27 0:16 ` Stephen Hemminger [this message]
2010-02-27 9:48 ` David Miller
2010-02-27 22:41 ` Dimitris Michailidis
-- strict thread matches above, loose matches on Subject: below --
2010-02-28 16:09 [PATCH 0/7] cxgb4: driver submission V4 Dimitris Michailidis
2010-02-28 16:09 ` [PATCH 1/7] cxgb4: Add register and message definitions Dimitris Michailidis
2010-02-28 16:09 ` [PATCH 2/7] cxgb4: Add FW API definitions Dimitris Michailidis
2010-02-28 16:09 ` [PATCH 3/7] cxgb4: Add HW and FW support code Dimitris Michailidis
2010-02-28 16:09 ` [PATCH 4/7] cxgb4: Add packet queues and packet DMA code Dimitris Michailidis
2010-02-27 1:42 Dimitrios Michailidis
2010-02-27 0:52 Dimitrios Michailidis
2010-02-27 1:31 ` Stephen Hemminger
2010-02-26 23:35 [PATCH 0/7] cxgb4: driver submission V3 Dimitris Michailidis
2010-02-26 23:35 ` [PATCH 1/7] cxgb4: Add register and message definitions Dimitris Michailidis
2010-02-26 23:35 ` [PATCH 2/7] cxgb4: Add FW API definitions Dimitris Michailidis
2010-02-26 23:35 ` [PATCH 3/7] cxgb4: Add HW and FW support code Dimitris Michailidis
2010-02-26 23:35 ` [PATCH 4/7] cxgb4: Add packet queues and packet DMA code Dimitris Michailidis
2010-02-26 23:57 ` Stephen Hemminger
2010-02-27 9:46 ` David Miller
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