linux-kernel - Re: [RFC PATCH v8 1/9] Restartable sequences system call

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Message-ID: <20160819212423.623v5leqknfrxhpd@x>
Date:   Fri, 19 Aug 2016 14:24:23 -0700
From:   Josh Triplett <josh@...htriplett.org>
To:     Andi Kleen <andi@...stfloor.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Peter Zijlstra <peterz@...radead.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Andy Lutomirski <luto@...capital.net>,
        Dave Watson <davejwatson@...com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        Paul Turner <pjt@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Russell King <linux@....linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Andrew Hunter <ahh@...gle.com>,
        Chris Lameter <cl@...ux.com>, Ben Maurer <bmaurer@...com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Michael Kerrisk <mtk.manpages@...il.com>
Subject: Re: [RFC PATCH v8 1/9] Restartable sequences system call

On Fri, Aug 19, 2016 at 01:56:11PM -0700, Andi Kleen wrote:
> > Nobody gets a cpu number just to get a cpu number - it's not a useful
> > thing to benchmark. What does getcpu() so much that we care?
> 
> malloc is the primary target I believe. Saves lots of memory to keep
> caches per CPU rather than per thread.

Also improves locality; that does seem like a good idea.  Has anyone
written and tested the corresponding changes to a malloc implementation?

- Josh Triplett