From: Josh Boyer <jwboyer@redhat.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
prarit@redhat.com, x86@kernel.org, linux-kernel@vger.kernel.org,
Russ Anderson <rja@sgi.com>
Subject: Re: [PATCH v3] x86/cpu: Allow higher NR_CPUS values
Date: Thu, 7 Nov 2013 08:51:08 -0500 [thread overview]
Message-ID: <20131107135107.GA595@hansolo.jdub.homelinux.org> (raw)
In-Reply-To: <20131107091555.GA2671@gmail.com>
On Thu, Nov 07, 2013 at 10:15:55AM +0100, Ingo Molnar wrote:
>
> * Josh Boyer <jwboyer@redhat.com> wrote:
>
> > The current range for SMP configs is 2 - 512 CPUs, or a full 4096 in the
> > case of MAXSMP. There are machines that have 1024 CPUs in them today
> > and configuring a kernel for that means you are forced to set MAXSMP.
> > This adds additional unnecessary overhead. While that overhead might be
> > considered tiny for large machines, it isn't necessarily so if you are
> > building a kernel that runs across a wide variety of machines.
> >
> > To cover the range of more common machines today, we allow NR_CPUS to be
> > up to 4096 when CPUMASK_OFFSTACK is enabled. Relatedly, we no longer make
> > that option depend on DEBUG_PER_CPU_MASKS.
>
> > index b3c8be0..50b47cd 100644
> > --- a/lib/Kconfig
> > +++ b/lib/Kconfig
> > @@ -342,7 +342,8 @@ config CHECK_SIGNATURE
> > bool
> >
> > config CPUMASK_OFFSTACK
> > - bool "Force CPU masks off stack" if DEBUG_PER_CPU_MAPS
> > + bool "Force CPU masks off stack"
> > + depends on SMP
> > help
> > Use dynamic allocation for cpumask_var_t, instead of putting
> > them on the stack. This is a bit more expensive, but avoids
>
> So this chunk really doesn't belong into the patch - it should be a
> separate patch.
>
> Also, because I already applied the patch (sans the unrelated chunk)
> please only send this single change against tip:master.
I missed that you removed that chunk, my mistake. I'll send a follow up
as you suggest.
josh
next prev parent reply other threads:[~2013-11-07 13:51 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-01 14:11 [PATCH] x86: Allow NR_CPUS=1024 Josh Boyer
2013-11-03 10:18 ` Ingo Molnar
2013-11-03 10:21 ` Ingo Molnar
2013-11-03 15:57 ` Josh Boyer
2013-11-03 17:43 ` H. Peter Anvin
2013-11-04 6:51 ` Ingo Molnar
2013-11-04 16:31 ` H. Peter Anvin
2013-11-04 6:53 ` Ingo Molnar
2013-11-04 14:01 ` Josh Boyer
2013-11-04 14:10 ` Ingo Molnar
2013-11-04 14:16 ` Josh Boyer
2013-11-04 14:54 ` Prarit Bhargava
2013-11-04 15:56 ` Russ Anderson
2013-11-04 17:48 ` Ingo Molnar
2013-11-04 19:08 ` H. Peter Anvin
2013-11-04 20:11 ` Ingo Molnar
2013-11-04 22:50 ` H. Peter Anvin
2013-11-05 6:25 ` Ingo Molnar
2013-11-05 6:31 ` Li Zefan
2013-11-03 14:29 ` Prarit Bhargava
2013-11-03 14:42 ` Russ Anderson
2013-11-05 14:37 ` [PATCH 1/2 v2] x86: Allow higher NR_CPUS values Josh Boyer
2013-11-05 14:38 ` [PATCH 2/2] x86: Increase MAXSMP CPU count to 8192 Josh Boyer
2013-11-06 5:56 ` [PATCH v2 " Ingo Molnar
2013-11-06 14:10 ` Josh Boyer
2013-11-06 11:20 ` [tip:x86/cpu] x86/cpu: Increase max " tip-bot for Josh Boyer
2013-11-06 7:15 ` [PATCH 1/2 v2] x86: Allow higher NR_CPUS values Ingo Molnar
2013-11-06 14:12 ` Josh Boyer
2013-11-06 15:04 ` Josh Boyer
2013-11-06 15:21 ` [PATCH v3] x86/cpu: " Josh Boyer
2013-11-07 9:15 ` Ingo Molnar
2013-11-07 13:51 ` Josh Boyer [this message]
2013-11-06 11:20 ` [tip:x86/cpu] " tip-bot for Josh Boyer
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