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From: Matt Fleming <matt@console-pimps.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>, Oleg Nesterov <oleg@redhat.com>,
	Tejun Heo <tj@kernel.org>,
	linux-kernel@vger.kernel.org, Tony Luck <tony.luck@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	David Mosberger-Tang <davidm@egauge.net>
Subject: Re: [RFC][PATCH 0/5] Signal scalability series
Date: Mon, 03 Oct 2011 16:43:33 +0100	[thread overview]
Message-ID: <1317656613.3375.78.camel@mfleming-mobl1.ger.corp.intel.com> (raw)
In-Reply-To: <CA+55aFyscb=PcUDrEUhFbH89+W-KYEKrqKHeNN3dqmZD1GF_Hw@mail.gmail.com>

On Mon, 2011-10-03 at 08:28 -0700, Linus Torvalds wrote:
> On Sat, Oct 1, 2011 at 2:35 AM, Matt Fleming <matt@console-pimps.org> wrote:
> >
> > You and me both. Unfortunately, the ia64 guys had a different opinion,
> > http://www.spinics.net/lists/linux-ia64/msg08363.html
> 
> Well, considering that it apparently slows down the single-threaded
> case by 50% on an architecture that actually *matters*, I think the
> whole discussion is somewhat academic, don't you?
> 
> "Scalability" is pretty much never a valid excuse for "slows down the
> common case".

Where did you get the 50% slow down figure from?

Oh, are you referring to Oleg's email about the slow down under kvm?
Yeah, admittedly that's a pretty clear indicator that something is wrong
with the approach in this patch series.

I thought I'd replied to that email but I guess not.

-- 
Matt Fleming, Intel Open Source Technology Center


  reply	other threads:[~2011-10-03 15:44 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-09-30 15:12 [RFC][PATCH 0/5] Signal scalability series Matt Fleming
2011-09-30 15:12 ` [RFC][PATCH 1/5] signal: Document signal locking rules Matt Fleming
2011-09-30 15:12 ` [RFC][PATCH 2/5] signal: Add rwlock to protect sighand->action Matt Fleming
2011-09-30 15:25   ` Peter Zijlstra
2011-09-30 15:56   ` Matt Fleming
2011-09-30 15:12 ` [RFC][PATCH 3/5] signal: Reduce sighand->siglock hold time in get_signal_to_deliver() Matt Fleming
2011-09-30 15:12 ` [RFC][PATCH 4/5] signal: Add signal->ctrl_lock for job control Matt Fleming
2011-09-30 15:30   ` Peter Zijlstra
2011-09-30 15:36     ` Matt Fleming
2011-09-30 15:12 ` [RFC][PATCH 5/5] signal: Split siglock into shared_siglock and per-thread siglock Matt Fleming
2011-09-30 16:52 ` [RFC][PATCH 0/5] Signal scalability series Oleg Nesterov
2011-09-30 18:54   ` Oleg Nesterov
2011-09-30 20:00   ` Matt Fleming
2011-09-30 23:56     ` Tejun Heo
2011-10-01 10:16       ` Matt Fleming
2011-10-01 13:03         ` Peter Zijlstra
2011-10-03  1:38           ` Tejun Heo
2011-10-03 13:56             ` Thomas Gleixner
2011-10-04  7:37               ` Tejun Heo
2011-10-03 13:07           ` Oleg Nesterov
2011-10-03 15:22             ` Peter Zijlstra
2011-10-04 17:14               ` Oleg Nesterov
2011-10-04 17:52                 ` Oleg Nesterov
2011-10-04 17:54                 ` Linus Torvalds
2011-10-04 18:13                   ` Oleg Nesterov
2011-10-03 13:16     ` Oleg Nesterov
2011-10-04  8:56       ` Matt Fleming
2011-10-04 17:29         ` Oleg Nesterov
2011-09-30 22:30 ` Andi Kleen
2011-10-01  9:35   ` Matt Fleming
2011-10-03 15:28     ` Linus Torvalds
2011-10-03 15:43       ` Matt Fleming [this message]
2011-10-03 16:35         ` Oleg Nesterov
2011-10-03 20:58           ` Matt Fleming
2011-10-03 21:45             ` Linus Torvalds
2011-10-03 22:13             ` Thomas Gleixner
2011-10-04  8:20               ` Matt Fleming
2011-10-04 17:39               ` Oleg Nesterov

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