[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20150612084251.GB9257@pd.tnic>
Date: Fri, 12 Jun 2015 10:42:51 +0200
From: Borislav Petkov <bp@...e.de>
To: Andy Lutomirski <luto@...capital.net>
Cc: Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
John Stultz <john.stultz@...aro.org>,
Aaron Lu <aaron.lu@...el.com>, Tony Li <tony.li@....com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Suravee Suthikulanit <suravee.suthikulpanit@....com>,
Frédéric Weisbecker <fweisbec@...il.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Fengguang Wu <fengguang.wu@...el.com>,
Len Brown <lenb@...nel.org>, Ken Xue <ken.xue@....com>,
Huang Rui <ray.huang@....com>, X86 ML <x86@...nel.org>
Subject: Re: [PATCH v2 3/4] x86, mwaitt: introduce mwaix delay with a
configurable timer
On Tue, Jun 09, 2015 at 09:46:52AM -0700, Andy Lutomirski wrote:
> I don't like this hack. The compiler is entirely within is rights to
> poke addr's cacheline (i.e. the stack) between the two instructions.
> I'd suggest either making the thing a full cacheline long or using a
> single asm statement.
How about this:
/*
* This should be a memory location in a cache line which is
* unlikely to be touched by other processors. The actual
* content is immaterial as it is not actually modified in any way.
*/
mwait_ptr = ¤t_thread_info()->flags;
and then
__monitor(mwait_ptr, 0, 0);
We already do this in mwait_play_dead().
However, am I even correct in assuming that ->flags won't really be
touched as we're doing delay() and nothing pokes into current anyway?
Thanks.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
--
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/
Powered by blists - more mailing lists