From: Tejun Heo <htejun@gmail.com>
To: Matt Fleming <matt@console-pimps.org>
Cc: Oleg Nesterov <oleg@redhat.com>,
linux-kernel@vger.kernel.org, Tony Luck <tony.luck@intel.com>
Subject: Re: [RFC][PATCH 0/5] Signal scalability series
Date: Fri, 30 Sep 2011 16:56:25 -0700 [thread overview]
Message-ID: <20110930235625.GD2658@mtj.dyndns.org> (raw)
In-Reply-To: <1317412823.3375.34.camel@mfleming-mobl1.ger.corp.intel.com>
Hello,
On Fri, Sep 30, 2011 at 09:00:23PM +0100, Matt Fleming wrote:
> On Fri, 2011-09-30 at 18:52 +0200, Oleg Nesterov wrote:
> Well, sighand->siglock is seriously overused. It protects so much and I
> think it's pretty confusing. It took me long enough to figure out how
> many locks were really needed. But that's beside the point, having a
> single lock doesn't scale at all, and that's what this series is about.
But scalability for what? What are the use cases here? Do we care
enough about benefits to those use cases to accept the increased
complexity? Having locks with broad coverage isn't necessarily evil.
If things are simpler that way and the protected paths aren't that
hot, who cares? If splitting the locking makes things simpler, sure
but that doesn't look like the case here, so we need pretty strong
rationale to justify the added complexity.
Thank you.
--
tejun
next prev parent reply other threads:[~2011-09-30 23:56 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-30 15:12 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 [this message]
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
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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