Con Kolivas wrote:
On Friday 26 May 2006 14:20, Peter Williams wrote:
These patches implement CPU usage rate limits for tasks.
Although the rlimit mechanism already has a CPU usage limit (RLIMIT_CPU)
it is a total usage limit and therefore (to my mind) not very useful.
These patches provide an alternative whereby the (recent) average CPU
usage rate of a task can be limited to a (per task) specified proportion
of a single CPU's capacity. The limits are specified in parts per
thousand and come in two varieties -- hard and soft. The difference
between the two is that the system tries to enforce hard caps regardless
of the other demand for CPU resources but allows soft caps to be
exceeded if there are spare CPU resources available. By default, tasks
will have both caps set to 1000 (i.e. no limit) but newly forked tasks
will inherit any caps that have been imposed on their parent from the
parent. The mimimim soft cap allowed is 0 (which effectively puts the
task in the background) and the minimim hard cap allowed is 1.
Care has been taken to minimize the overhead inflicted on tasks that
have no caps and my tests using kernbench indicate that it is hidden in
the noise.
The presence of tasks with caps will break smp balancing and smp nice. I
suspect you could probably provide a reasonable workaround by altering their
priority bias effect in the raw weighted load in smp nice for soft caps by
the percentage cpu of the cap. Hard caps provide more "interesting"
challenges though. I can't think of a valid biasing off hand for them, but at
least initially using the same logic as soft caps should help.
I thought that I already did that? Check the changes to set_load_weight().
--
Peter Williams [email protected]
"Learning, n. The kind of ignorance distinguishing the studious."
-- Ambrose Bierce
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
