linux-kernel - Re: [PATCH 7/8] sched, net: Fixup busy_loop_us

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]

Message-ID: <529773FC.6020707@linux.intel.com>
Date:	Thu, 28 Nov 2013 18:49:00 +0200
From:	Eliezer Tamir <eliezer.tamir@...ux.intel.com>
To:	Peter Zijlstra <peterz@...radead.org>,
	Arjan van de Ven <arjan@...ux.intel.com>, lenb@...nel.org,
	rjw@...ysocki.net, David Miller <davem@...emloft.net>,
	rui.zhang@...el.com, jacob.jun.pan@...ux.intel.com,
	Mike Galbraith <bitbucket@...ine.de>,
	Ingo Molnar <mingo@...nel.org>, hpa@...or.com,
	Thomas Gleixner <tglx@...utronix.de>
CC:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 7/8] sched, net: Fixup busy_loop_us_clock()

On 26/11/2013 17:57, Peter Zijlstra wrote:
> 
> Replace sched_clock() usage with local_clock() which has a bounded
> drift between CPUs (<2 jiffies).
> 

Peter,

I have tested this patch and I see a performance regression of about
1.5%.

Maybe it would be better, rather then testing in the fast path, to
simply disallow busy polling altogether when sched_clock_stable is
not true?

Thanks,
Eliezer
--
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/