From mboxrd@z Thu Jan  1 00:00:00 1970
From: Linus Torvalds <torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Subject: Re: [RFC PATCH v8 1/9] Restartable sequences system call
Date: Fri, 19 Aug 2016 14:32:13 -0700
Message-ID: <CA+55aFwo7LJ95fKBAhzcu6kCLd5=73n9M6QOq-mMaYO-d5dCVw@mail.gmail.com>
References: <1471637274-13583-1-git-send-email-mathieu.desnoyers@efficios.com>
 <1471637274-13583-2-git-send-email-mathieu.desnoyers@efficios.com>
 <CA+55aFz+Q33m1+ju3ANaznBwYCcWo9D9WDr2=p0YLEF4gJF12g@mail.gmail.com>
 <20160819205611.GF5871@two.firstfloor.org> <20160819211946.GJ3482@linux.vnet.ibm.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Return-path: <linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
In-Reply-To: <20160819211946.GJ3482-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
To: Paul McKenney <paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
Cc: Andi Kleen <andi-Vw/NltI1exuRpAAqCnN02g@public.gmane.org>, Mathieu Desnoyers <mathieu.desnoyers-vg+e7yoeK/dWk0Htik3J/w@public.gmane.org>, Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, Boqun Feng <boqun.feng-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>, Dave Watson <davejwatson-b10kYP2dOMg@public.gmane.org>, Linux Kernel Mailing List <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Linux API <linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Paul Turner <pjt-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Russell King <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>, Andrew Hunter <ahh-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Chris Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org>, Ben Maurer <bmaurer-b10kYP2dOMg@public.gmane.org>, Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org>, Josh Triplett <josh-iaAMLnmF4UmaiuxdJuQwMA@public.gmane.org>, Catalin Marinas <catalin.marinas-5wv7dgnIgG8@public.gmane.org>
List-Id: linux-api@vger.kernel.org

On Fri, Aug 19, 2016 at 2:19 PM, Paul E. McKenney
<paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org> wrote:
> On Fri, Aug 19, 2016 at 01:56:11PM -0700, Andi Kleen wrote:
>>
>> malloc is the primary target I believe. Saves lots of memory to keep
>> caches per CPU rather than per thread.
>
> Agreed, a competent default malloc() in glibc would be a very nice change
> from the current state.

I agree that malloc can be a very good target for something like this,
but it is also something that is quite complicated. A general-purpose
allocator that could be used by glibc and has not just the performance
but the debug stuff etc that people inevitably want is a big project.
And then the people who have special needs end up writing their own
allocators anyway, just because they care about certain layout and
access patterns...

Put another way: I'd really like to see some real numbers and use,
rather than "this can be used for.."

             Linus