linux-kernel - Re: Proper kernel irq time accounting -v3

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:	Thu, 30 Sep 2010 09:37:17 -0700
From:	Venkatesh Pallipadi <venki@...gle.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, Paul Turner <pjt@...gle.com>,
	Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: Proper kernel irq time accounting -v3

On Thu, Sep 30, 2010 at 12:59 AM, Andi Kleen <andi@...stfloor.org> wrote:
> Venkatesh Pallipadi <venki@...gle.com> writes:
>>
>> Solution to (1) involves adding extra timing on irq entry/exit to
>> get the fine granularity info and then exporting it to user.
>
> This means RDTSC right?
>
> I am a bit concerned about overhead on systems with high TSC overhead.
> Is there a way to turn this off at runtime for those?
>

Yes. Overhead will be RDTSC.
notsc is a boot option that will disable this. I didn't want to have a
specific run time option to disable this as we would already have
other RDTSC users like native_sched_clock. Do you think we need a
specific option to disable this feature? I don't like adding a runtime
option because it complicates the code a bit (to handle things like
someone turning it off and turning it on later, etc).

Thanks,
Venki
--
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/