linux-kernel - Re: [PATCH RFC] perf: x86: Improve accuracy of perf/sched clock

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] [day] [month] [year] [list]

Message-ID: <20150724150301.GJ19282@twins.programming.kicks-ass.net>
Date:	Fri, 24 Jul 2015 17:03:01 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Adrian Hunter <adrian.hunter@...el.com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org,
	Stephane Eranian <eranian@...gle.com>,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH RFC] perf: x86: Improve accuracy of perf/sched clock

On Fri, Jul 24, 2015 at 04:39:55PM +0300, Adrian Hunter wrote:
> @@ -251,17 +253,17 @@ static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
>  	rdtscll(tsc_now);
>  	ns_now = cycles_2_ns(tsc_now);
>  
> -	/*
> -	 * Compute a new multiplier as per the above comment and ensure our
> -	 * time function is continuous; see the comment near struct
> -	 * cyc2ns_data.
> -	 */

I'd leave this comment, but update the one this refers to; esp. the bit
that explains why 10.

Also, I think you can remove the definition of CYC2NS_SCALE_FACTOR.

Other than that, seems like a good idea.
--
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/