From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Olsa Subject: Re: [PATCH RESEND v4] perf/core: Fix installing cgroup event into cpu Date: Thu, 8 Feb 2018 16:36:48 +0100 Message-ID: <20180208153648.GC12817@krava> References: <20180208033344.71933-1-linxiulei@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20180208033344.71933-1-linxiulei@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: linxiulei@gmail.com Cc: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, alexander.shishkin@linux.intel.com, tglx@linutronix.de, eranian@gmail.com, torvalds@linux-foundation.org, brendan.d.gregg@gmail.com, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, yang_oliver@hotmail.com, jinli.zjl@alibaba-inc.com, "leilei.lin" List-Id: linux-perf-users.vger.kernel.org On Thu, Feb 08, 2018 at 11:33:44AM +0800, linxiulei@gmail.com wrote: > From: "leilei.lin" > > 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 > --- > 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; I might be missing something, but should this check stay on the top regardles of the cgroup_is_descendant check below? you could put NULL into cpuctx->cgrp on context with cgroup event in the list thanks, jirka > /* > * 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; SNIP