From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick Ohly Subject: Re: hardware time stamping with optional structs in data area Date: Wed, 28 Jan 2009 10:52:13 +0100 Message-ID: <1233136333.26507.38.camel@pohly-MOBL> References: <20090128090821.GA15770@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090128090821.GA15770-lOAM2aK0SrRLBo1qDEOMRrpzq4S04n8Q@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Herbert Xu Cc: "davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-api@vger.kernel.org On Wed, 2009-01-28 at 11:08 +0200, Herbert Xu wrote: > Patrick Ohly wrote: > > > > True - at this time. But what if this extension mechanism turns out to > > be useful and we end up with more optional structures? I was hoping that > > this might be the case and thus tried to make it easy to add more > > structures. > > You're putting the extension in the skb->end area, right? Right. > How big are the time stamps? If they're not that big, why don't > we put it into the shinfo structure itself? For the common case, > we have plenty of space due to kmalloc padding anyway. Two 64 bit fields have to be added for time stamps plus 3 bits for flags (for time stamping instructions, currently in skb_shared_tx). Putting that into shinfo should work fine. I thought extending that structure with information that isn't needed for all packets was as bad as extending sk_buff itself. If that isn't the case, then extending shinfo definitely is the simplest solution. Bye, Patrick -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html