linux-kernel - Re: [PATCH 0/4] Finer granularity and task/cgroup irq time accounting

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 24 Aug 2010 18:17:26 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Venkatesh Pallipadi <venki@...gle.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Paul Menage <menage@...gle.com>, linux-kernel@...r.kernel.org,
	Paul Turner <pjt@...gle.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Paul Mackerras <paulus@...ba.org>,
	Tony Luck <tony.luck@...el.com>
Subject: Re: [PATCH 0/4] Finer granularity and task/cgroup irq time accounting

* Peter Zijlstra <peterz@...radead.org> [2010-08-24 13:53:55]:

> On Tue, 2010-08-24 at 17:08 +0530, Balbir Singh wrote:
> > 
> > The point is for containers it is more likely to give the right answer
> > and so on. Yes, the results are not 100% accurate. 
> 
> Consider one group heavily dirtying pages, it stuffs the IO queues full
> and gets blocked on IO completion. Since the CPU is then free to
> schedule something else we start running things from another group,
> those IO completions will come in while we run other group and get
> accounted to other group -- FAIL.
> 
> s/group/task/ etc..
> 
> That just really doesn't work, accounting async work, esp stuff that is
> not under software control it very tricky indeed.

Yes, we don't have sufficient context to charge the correct context. I
think openvz has some technology there, we will too when we have I/O
cgroups at a cgroup level, but the instances of such operations are
too many to accurately identify them all.

> 
> So what are you wanting to do, and why. Do you really need accounting
> madness?

I think Venki gave the answer in the posting

"There are usecases where reporting this time against task
or task groups or cgroups will be useful for user/administrator
in terms of resource planning and utilization charging"

I don't have any specific use cases, I was just reviewing the patchset
and trying to understand how to solve the problem.


-- 
	Three Cheers,
	Balbir
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/