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Subject: Re: [GIT PULL] Re: REGRESSION: Performance regressions from switching anon_vma->lock to mutex
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 15 Jun 2011 13:47:33 -0700
To: paulmck@linux.vnet.ibm.com, Ingo Molnar <mingo@elte.hu>
CC: Peter Zijlstra <peterz@infradead.org>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        David Miller <davem@davemloft.net>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Russell King <rmk@arm.linux.org.uk>, Paul Mundt <lethal@linux-sh.org>,
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        Tony Luck <tony.luck@intel.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@kernel.dk>,
        Namhyung Kim <namhyung@gmail.com>, ak@linux.intel.com,
        shaohua.li@intel.com, alex.shi@intel.com, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, "Rafael J. Wysocki" <rjw@sisk.pl>
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"Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:
>
>It would be much lower risk to make the current code always use softirq
>if !RCU_BOOST -- last time I attempted the revert, it was quite hairy.

I don't care if it's a real revert or not, but I want the threads gone. Entirely. Not just the patch that uses softirqs for some things, and threads for the callbacks. No, I don't want the threads to show up or exist at all.

And to be sure, I'd like the code to set up and use the threads to actually compile away statically, so that there clearly isn't some way it's partially enabled.

        Linus
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