Hello,
On Mon, Nov 14, 2016 at 02:22:12PM -0800, Shaohua Li wrote:
> +static unsigned long tg_last_high_overflow_time(struct throtl_grp *tg)
> +{
> + struct throtl_service_queue *parent_sq;
> + struct throtl_grp *parent = tg;
> + unsigned long ret = __tg_last_high_overflow_time(tg);
> +
> + while (true) {
> + parent_sq = parent->service_queue.parent_sq;
> + parent = sq_to_tg(parent_sq);
> + if (!parent)
> + break;
> + if (((parent->bps[READ][LIMIT_HIGH] != -1 &&
> + parent->bps[READ][LIMIT_HIGH] >=
> + tg->bps[READ][LIMIT_HIGH]) ||
> + (parent->bps[READ][LIMIT_HIGH] == -1 &&
> + parent->bps[READ][LIMIT_MAX] >=
> + tg->bps[READ][LIMIT_HIGH])) &&
> + ((parent->bps[WRITE][LIMIT_HIGH] != -1 &&
> + parent->bps[WRITE][LIMIT_HIGH] >=
> + tg->bps[WRITE][LIMIT_HIGH]) ||
> + (parent->bps[WRITE][LIMIT_HIGH] == -1 &&
> + parent->bps[WRITE][LIMIT_MAX] >=
> + tg->bps[WRITE][LIMIT_HIGH])) &&
> + ((parent->iops[READ][LIMIT_HIGH] != -1 &&
> + parent->iops[READ][LIMIT_HIGH] >=
> + tg->iops[READ][LIMIT_HIGH]) ||
> + (parent->iops[READ][LIMIT_HIGH] == -1 &&
> + parent->iops[READ][LIMIT_MAX] >=
> + tg->iops[READ][LIMIT_HIGH])) &&
> + ((parent->iops[WRITE][LIMIT_HIGH] != -1 &&
> + parent->iops[WRITE][LIMIT_HIGH] >=
> + tg->iops[WRITE][LIMIT_HIGH]) ||
> + (parent->iops[WRITE][LIMIT_HIGH] == -1 &&
> + parent->iops[WRITE][LIMIT_MAX] >=
> + tg->iops[WRITE][LIMIT_HIGH])))
> + break;
> + if (time_after(__tg_last_high_overflow_time(parent), ret))
> + ret = __tg_last_high_overflow_time(parent);
> + }
> + return ret;
> +}
Heh, I'm not really following the upgrade/downgrade logic. I'm having
trouble understanding two things.
1. A cgroup and its high and max limits don't have much to do with
other cgroups and their limits. I don't get how the choice between
high and max limits can be a td-wide state.
2. Comparing parent's and child's limits and saying that either can be
ignored because one is higher than the other isn't correct. A
parent's limit doesn't apply to each child separately. It has to
be aggregated. e.g. you can ignore a parent's setting if the sum
of all children's limits is smaller than the parent's but then
again there could still be a lower limit higher up the tree, so
they would still have to be examined.
Thanks.
--
tejun
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