Messages in this thread |  | | | Date | Wed, 16 Nov 2005 13:07:26 -0800 | | From | Paul Jackson <> | | Subject | Re: [RFC] [PATCH 00/13] Introduce task_pid api |
| |
> Could we switch > to 128-bits so that pids are never reused or something like that?
Not easily. We've got a very cool pid-dispenser at this point that has excellent performance and scalability, but requires a bit map, one bit per potential pid. That bitmap can't exceed a small percentage of main memory on most any configuration, constraining us to perhaps 20 to 30 bits. The code currently has a 22 bit arbitrary limit. Something like 30 bits would usually only make sense on the terabyte NUMA monster boxes.
128-bit UUID technology scales fine, but adds quite a few compute cycles per allocation, and would blow out a whole lot of user code expecting to put a pid in a machine word.
-- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson <pj@sgi.com> 1.925.600.0401 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |