In article <200307041357.32871.jeffpc@optonline.net> you wrote:
> If one cpu tries to read a u_int64_t variable while another tries to
> update it, the worst case scenario is that the reader will get the high
> 32-bits before the write, and low 32-bit after the write, now if the counter
> overflow, the number would be off by 4GB! (This only applies to 32-bit
> architectures.) True, there are cache coherency algorithms, etc...
a reader like ifconfig can easyly work around this with multiple tries, but
incremeting those variables wont work that easy, and therefore needs a lock,
which will be a major pita.
64bit counters should be a result of lockless per-cpu network counters
(32bit) with some kind of async merging.
Or we wait till 64bit hardware is more common :)
Greetings
Bernd
-- eckes privat - http://www.eckes.org/ Project Freefire - http://www.freefire.org/ - 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/
This archive was generated by hypermail 2b29 : Mon Jul 07 2003 - 22:00:25 EST