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From: Tejun Heo <tj@kernel.org>
To: Song Liu <song@kernel.org>
Cc: Yosry Ahmed <yosryahmed@google.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Johannes Weiner <hannes@cmpxchg.org>, Hao Luo <haoluo@google.com>,
	Shakeel Butt <shakeelb@google.com>,
	Stanislav Fomichev <sdf@google.com>,
	David Rientjes <rientjes@google.com>, bpf <bpf@vger.kernel.org>,
	KP Singh <kpsingh@kernel.org>,
	cgroups@vger.kernel.org, Linux-MM <linux-mm@kvack.org>
Subject: Re: [RFC bpf-next] Hierarchical Cgroup Stats Collection Using BPF
Date: Wed, 16 Mar 2022 06:31:21 -1000	[thread overview]
Message-ID: <YjIQ2c8CoMDDaUeT@slm.duckdns.org> (raw)
In-Reply-To: <CAPhsuW5qHSZNSEh8CQK3wYqtJ4XB+EwFEJWKA9SkA+wGFbvNCg@mail.gmail.com>

On Tue, Mar 15, 2022 at 11:04:56PM -0700, Song Liu wrote:
> Lookups invoke a rstat flush, so we still walk every node of a subtree for
> each lookup, no? So the actual cost should be similar than walking the
> subtree with some BPF program? Did I miss something?

rstat only walks cgroups / cpus which have been active since the flush.

Thanks.

-- 
tejun

WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Song Liu <song-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Yosry Ahmed <yosryahmed-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Alexei Starovoitov <ast-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Andrii Nakryiko <andrii-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Daniel Borkmann <daniel-FeC+5ew28dpmcu3hnIyYJQ@public.gmane.org>,
	Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
	Hao Luo <haoluo-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Stanislav Fomichev <sdf-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	David Rientjes <rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	bpf <bpf-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	KP Singh <kpsingh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Linux-MM <linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>
Subject: Re: [RFC bpf-next] Hierarchical Cgroup Stats Collection Using BPF
Date: Wed, 16 Mar 2022 06:31:21 -1000	[thread overview]
Message-ID: <YjIQ2c8CoMDDaUeT@slm.duckdns.org> (raw)
In-Reply-To: <CAPhsuW5qHSZNSEh8CQK3wYqtJ4XB+EwFEJWKA9SkA+wGFbvNCg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Tue, Mar 15, 2022 at 11:04:56PM -0700, Song Liu wrote:
> Lookups invoke a rstat flush, so we still walk every node of a subtree for
> each lookup, no? So the actual cost should be similar than walking the
> subtree with some BPF program? Did I miss something?

rstat only walks cgroups / cpus which have been active since the flush.

Thanks.

-- 
tejun

  parent reply	other threads:[~2022-03-16 16:31 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-09 20:27 [RFC bpf-next] Hierarchical Cgroup Stats Collection Using BPF Yosry Ahmed
2022-03-09 20:27 ` Yosry Ahmed
2022-03-14  5:35 ` Tejun Heo
2022-03-16 16:35   ` Yosry Ahmed
2022-03-22 18:09     ` Yonghong Song
2022-03-22 21:37       ` Hao Luo
2022-03-22 22:06         ` Yonghong Song
2022-03-28  9:22       ` Yosry Ahmed
2022-03-28  9:22         ` Yosry Ahmed
2022-03-16  6:04 ` Song Liu
2022-03-16 16:11   ` Yosry Ahmed
2022-03-16 16:13   ` Yosry Ahmed
2022-03-16 16:13     ` Yosry Ahmed
2022-03-16 16:31   ` Tejun Heo [this message]
2022-03-16 16:31     ` Tejun Heo
2022-03-18 19:59 ` Song Liu
2022-03-28  9:16   ` Yosry Ahmed
2022-03-28  9:16     ` Yosry Ahmed

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