From ee4a78998eebb12bbc55e47e8c154c5e119cc5c9 Mon Sep 17 00:00:00 2001
From: Robert Watson <rwatson@FreeBSD.org>
Date: Sat, 20 Mar 2010 12:02:16 +0000
Subject: [PATCH] Combine two suggestions from Attilio for potential
 SMP-related GSoC projects, and list him and jhb as potential contacts.

---
 en/projects/ideas/ideas.xml | 38 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/en/projects/ideas/ideas.xml b/en/projects/ideas/ideas.xml
index 7ef20af860..660b225a51 100644
--- a/en/projects/ideas/ideas.xml
+++ b/en/projects/ideas/ideas.xml
@@ -15,7 +15,7 @@ Ideas//EN"
 <ideas>
   <cvs:keywords xmlns:cvs="http://www.FreeBSD.org/XML/CVS" version="1.0">
     <cvs:keyword name="freebsd">
-      $FreeBSD: www/en/projects/ideas/ideas.xml,v 1.145 2010/03/14 15:52:47 rwatson Exp $
+      $FreeBSD: www/en/projects/ideas/ideas.xml,v 1.146 2010/03/15 17:58:35 imp Exp $
     </cvs:keyword>
   </cvs:keywords>
 
@@ -444,6 +444,42 @@ these buses to be a subclass of this new base class.</p>
       </desc>
     </idea>
 
+    <idea id="scalableprimitives" class="soc">
+      <title>SMP scalability improvements for core primitives</title>
+      <desc>
+	<p><strong>Technical contact</strong>: <a
+	  href="mailto:attilio@FreeBSD.org">Attilio Rao</a>, <a
+	  href="mailto:jhb@FreeBSD.org">John Baldwin</a>.</p>
+
+	<p>FreeBSD SMP scalability has improved dramatically over the last
+	  ten years as a result of the now-complete SMPng project, which
+	  converted FreeBSD from a single Giant kernel lock to fine-grained
+	  locking and strong 8-core scalability.  As commodity hardware is
+	  now reaching 16-24 cores, some low-level primitives in the SMP
+	  implementation must be revisited.  In particular, 32 or 64-CPU
+	  limits are encoded in the CPU mask primitive (cpumask_t), and
+	  spin locks offer higher than desired cache line contention as well
+	  as unfairness.  This project would combine these two related tasks
+	  by improving the expressibility of CPU masks and per-CPU objects
+	  and improving the scalability of the spinlock implementation.  It
+	  is especially important that the latter portion of the work be
+	  driven by real-world measurement using workloads that trigger the
+	  specific problem, and experimentation with primitives across
+	  several types of hardware.</p>
+
+	<p>Note: a spinlock backoff patch has already been proposed, but not
+	  yet properly evaluated, and would make a good starting point for
+	  this work.</p>
+
+	<p><strong>Requirements</strong>:</p>
+	<ul>
+	  <li>Strong knowledge of C.</li>
+	  <li>Experience with multi-threaded programming.</li>
+	  <li>Experience with kernel programming.</li>
+	</ul>
+      </desc>
+    </idea>
+
       <idea id="docsysctl">
         <title>Document all sysctls</title>
         <desc>