Messages in this thread | | | Date | Tue, 14 Feb 2006 00:22:37 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 08/13] hrtimer: remove data field |
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* Roman Zippel <zippel@linux-m68k.org> wrote:
> On Mon, 13 Feb 2006, Ingo Molnar wrote: > > > > The nanosleep cleanup allows to remove the data field of hrtimer. The > > > callback function can use container_of() to get it's own data. Since > > > the hrtimer structure is usually embedded in other structures, the > > > code also becomes a bit simpler. > > > > i addressed this when you first raised this issue (back in the ktimers > > flamewars), and generally the feeling of people i asked was that doing > > the container_of() approach is less readable than an explicit 'data' > > field. It also deviates from struct timer_list, which we wanted to stay > > close to. Furthermore, for standalone hrtimers this creates the need to > > generate a wrapper structure. So i dont really like this change - but no > > strong feelings either way. > > With the complete size reduction struct hrtimer becomes 32 bytes on 32 > bits archs and so we can fit the basic hrtimer into one or two cache > lines. container_of() is becoming more and more common in the kernel, > so I don't know who asked, it's not that difficult to use. I agree it > makes simple test modules a bit more difficult, but so far the more > common case is that this structure is embedded in other structures and > container_of() creates simpler code. Additionally you get type > checking for free, which you don't get with a void pointer.
yeah, i agreed with you back then too. (in fact i raised doing the same for timer_list, which is embedded in other structs quite frequently too, but this thought didnt acquire much traction either.)
But clearly this is not a must-have item for 2.6.16.
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