All of lore.kernel.org
 help / color / mirror / Atom feed
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Matt Fleming <matt@console-pimps.org>
Cc: Tejun Heo <htejun@gmail.com>, Oleg Nesterov <oleg@redhat.com>,
	linux-kernel@vger.kernel.org, Tony Luck <tony.luck@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC][PATCH 0/5] Signal scalability series
Date: Sat, 01 Oct 2011 15:03:29 +0200	[thread overview]
Message-ID: <1317474209.12973.15.camel@twins> (raw)
In-Reply-To: <1317464192.3375.57.camel@mfleming-mobl1.ger.corp.intel.com>

On Sat, 2011-10-01 at 11:16 +0100, Matt Fleming wrote:
> I also think Thomas/Peter mentioned something about latency in
> delivering timer signals because of contention on the per-process
> siglock. They might have some more details on that. 

Right, so signal delivery is O(nr_threads), which precludes being able
to deliver signals from hardirq context, leading to lots of ugly in -rt.

The hope is that this work is a stepping stone to O(1) signal delivery.

Breaking up the multitude of uses of siglock certainly seems worthwhile
esp. if it also allows for a cleanup of the horrid mess called
signal_struct (which really should be called process_struct or so).

And yes, aside from that the siglock can be quite contended because its
pretty much the one lock serializing all of the process wide state.

  reply	other threads:[~2011-10-01 13:04 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 [this message]
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1317474209.12973.15.camel@twins \
    --to=a.p.zijlstra@chello.nl \
    --cc=htejun@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=matt@console-pimps.org \
    --cc=oleg@redhat.com \
    --cc=tglx@linutronix.de \
    --cc=tony.luck@intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.