On Wed, Jan 24, 2018 at 03:50:10PM +0800, [email protected] wrote: > From: "leilei.lin" <[email protected]> > > Do not install cgroup event into the CPU context 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 changelog doesn't really cover the extend of the changes done. > Signed-off-by: leilei.lin <[email protected]> > --- > kernel/events/core.c | 44 +++++++++++++++++++++++++++++++------------- > 1 file changed, 31 insertions(+), 13 deletions(-) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 4df5b69..f766b60 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -933,31 +933,36 @@ 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; > > /* > * Because cgroup events are always per-cpu events, > * this will always be called from the right CPU. > */ > cpuctx = __get_cpu_context(ctx); > + cgrp = perf_cgroup_from_task(current, ctx); > > + /* cpuctx->cgrp is NULL unless a cgroup event is running in this CPU .*/ > + if (cgroup_is_descendant(cgrp->css.cgroup, event->cgrp->css.cgroup)) { > + if (add) > cpuctx->cgrp = cgrp; > + 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); > } I'm a little confused; you unconditionally set cpuctx->cgrp for every add/delete. So if we have >1 cgroup events on, and we remove one, you still clear cpuctx->cgrp, that seems wrong. Why did you change that? The Changelog doesn't include enough clues for me to know what you were trying to do.
