Re: [PATCH] change pts allocation behaviour in

[Steve Young <sdyoung@vt220.org>]

On Fri, May 07, 2004 at 04:14:42AM -0700, Andrew Morton wrote:
> >  in the range of 0-255 first.  However, if that fails, then it will search the
> >  higher ranges. 
> 
> Wouldn't we be better off with plain old first-fit-from-zero?

  In the typical case where <256 pts devices are allocated, you're right that
there will be no benefit over the first-fit-from-zero implementation.  However 
when there are a lot of pts devices in use, the algorithm used for searching 
the high ranges ought to generally find a new pts in fewer iterations than
just linearly searching from 0 to the maximum pts number.  For example, if a 
system allocates 5000 ptses in a row, when it goes to look for a new one with 
first-fit-from-zero, that's 5001 iterations to find an available pts.  Using
the patch though, it will only take 257 iterations.  As time goes on and 
ptses get allocated and freed the situation becomes a bit murkier, but 
the patch should still cut down the number of iterations required to find
a free pts.

  Thanks,
  Steve.