From: "leilei.lin" <leilei....@alibaba-inc.com> Do not install cgroup event into the CPU context and schedule it if the cgroup is not running on this CPU
While there is no task of cgroup running specified CPU, current kernel still install cgroup event into CPU context that causes another cgroup event can't be installed into this CPU. This patch prevent scheduling events at __perf_install_in_context() and installing events at list_update_cgroup_event() if cgroup isn't running on specified CPU. Signed-off-by: leilei.lin <leilei....@alibaba-inc.com> --- v2: Set cpuctx->cgrp only if the same cgroup is running on this CPU otherwise following events couldn't be activated immediately v3: Enhance the comments and commit message v4: Adjust to config kernel/events/core.c | 50 +++++++++++++++++++++++++++++++++++++------------- 1 file changed, 37 insertions(+), 13 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 4df5b69..fd28d61 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -933,31 +933,41 @@ list_update_cgroup_event(struct perf_event *event, { struct perf_cpu_context *cpuctx; struct list_head *cpuctx_entry; + struct perf_cgroup *cgrp; if (!is_cgroup_event(event)) return; - if (add && ctx->nr_cgroups++) - return; - else if (!add && --ctx->nr_cgroups) - return; /* * Because cgroup events are always per-cpu events, * this will always be called from the right CPU. */ cpuctx = __get_cpu_context(ctx); - cpuctx_entry = &cpuctx->cgrp_cpuctx_entry; - /* cpuctx->cgrp is NULL unless a cgroup event is active in this CPU .*/ - if (add) { - struct perf_cgroup *cgrp = perf_cgroup_from_task(current, ctx); + cgrp = perf_cgroup_from_task(current, ctx); - list_add(cpuctx_entry, this_cpu_ptr(&cgrp_cpuctx_list)); - if (cgroup_is_descendant(cgrp->css.cgroup, event->cgrp->css.cgroup)) + /* + * if only the cgroup is running on this cpu, + * we put/remove this cgroup into cpu context. + * Or it would case mismatch in following cgroup + * events at event_filter_match() + */ + if (cgroup_is_descendant(cgrp->css.cgroup, event->cgrp->css.cgroup)) { + if (add) cpuctx->cgrp = cgrp; - } else { - list_del(cpuctx_entry); - cpuctx->cgrp = NULL; + else + cpuctx->cgrp = NULL; } + + if (add && ctx->nr_cgroups++) + return; + else if (!add && --ctx->nr_cgroups) + return; + + cpuctx_entry = &cpuctx->cgrp_cpuctx_entry; + if (add) + list_add(cpuctx_entry, this_cpu_ptr(&cgrp_cpuctx_list)); + else + list_del(cpuctx_entry); } #else /* !CONFIG_CGROUP_PERF */ @@ -2311,6 +2321,20 @@ static int __perf_install_in_context(void *info) raw_spin_lock(&task_ctx->lock); } +#ifdef CONFIG_CGROUP_PERF + if (is_cgroup_event(event)) { + /* + * Only care about cgroup events. + * + * If only the task belongs to cgroup of this event, + * we will continue the installment + */ + struct perf_cgroup *cgrp = perf_cgroup_from_task(current, ctx); + reprogram = cgroup_is_descendant(cgrp->css.cgroup, + event->cgrp->css.cgroup); + } +#endif + if (reprogram) { ctx_sched_out(ctx, cpuctx, EVENT_TIME); add_event_to_ctx(event, ctx); -- 2.8.4.31.g9ed660f