On Mon, Mar 03, 2014 at 04:03:59PM -0500, George Spelvin wrote:
> > struct fd {
> > struct file *file;
> > - int need_put;
> > + unsigned need_put:1, need_pos_unlock:1;
> > };
>
> Since we're rounding up to 2*sizeof(struct file *) anyway, is this a case
> where wasting space on a couple of char (or bool) flags would generate
> better code than a bitfield?
>
> In particular, the code to set need_pos_unlock (which will be executed
> each read/write for most files) is messy in the bitfield case.
> A byte store is much cleaner.
>
> (If you want to use bits, why not use the two lsbits of the file pointer
> for the purpose? That would save a lot of space.)
Most of the cases have it kept separately in registers, actually - there's
a reason why fdget() and friends are inlined.
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