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From: "tj@kernel.org" <tj@kernel.org>
To: "Wlodarczyk, Bertrand" <bertrand.wlodarczyk@intel.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>,
	"hannes@cmpxchg.org" <hannes@cmpxchg.org>,
	"mkoutny@suse.com" <mkoutny@suse.com>,
	"cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"inwardvessel@gmail.com" <inwardvessel@gmail.com>
Subject: Re: [PATCH v2] cgroup/rstat: change cgroup_base_stat to atomic
Date: Fri, 27 Jun 2025 06:50:58 -1000	[thread overview]
Message-ID: <aF7L8jRkWm1TrwSu@slm.duckdns.org> (raw)
In-Reply-To: <CH3PR11MB7894DDEE6C630D5A3A4D23A1F145A@CH3PR11MB7894.namprd11.prod.outlook.com>

Hello,

On Fri, Jun 27, 2025 at 01:15:31PM +0000, Wlodarczyk, Bertrand wrote:
...
>  > Also the response to the tearing issue explained by JP is not satisfying.
> 
> In other words, the claim is: "it's better to stall other cpus in spinlock plus disable IRQ every time in order to 
> serve outdated snapshot instead of providing user to the freshest statistics much, much faster".
> In term of statistics, freshest data served fast to the user is, in my opinion, better behavior.

This is a false choice, I think. e.g. We can easily use seqlock to remove
strict synchronization only from user side, right?

> I wouldn't be addressing this issue if there were no customers affected by rstat latency in multi-container
> multi-cpu scenarios.

Out of curiosity, can you explain the case that you observed in more detail?
What were the customer doing?

Thanks.

-- 
tejun

  reply	other threads:[~2025-06-27 16:51 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-24 14:45 [PATCH v2] cgroup/rstat: change cgroup_base_stat to atomic Bertrand Wlodarczyk
2025-06-26 19:15 ` Shakeel Butt
2025-06-27 13:15   ` Wlodarczyk, Bertrand
2025-06-27 16:50     ` tj [this message]
2025-06-30 14:25       ` Wlodarczyk, Bertrand
2025-06-30 15:48         ` tj
2025-07-04 13:13           ` Wlodarczyk, Bertrand
2025-07-04 17:57             ` tj
2025-07-21 11:48               ` Wlodarczyk, Bertrand
2025-06-27 16:55     ` JP Kobryn
2025-06-27 17:17     ` Shakeel Butt

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