From 181fe4144e00e269ddc9471712a312d0ad4c8ab8 Mon Sep 17 00:00:00 2001
From: Murray Stokely <murray@FreeBSD.org>
Date: Sun, 11 Mar 2007 06:58:12 +0000
Subject: [PATCH] Add project about avoiding syscall overhead for some userland
 requests such as setproctitle().  Suitable for SoC with right mentor.

Submitted by:	kris
Additional text by:	rwatson
---
 en/projects/ideas/ideas.xml | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/en/projects/ideas/ideas.xml b/en/projects/ideas/ideas.xml
index 8c893e4c92..ae519b8e43 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 1.4 2007/03/10 07:37:44 murray Exp $
+      $FreeBSD: www/en/projects/ideas/ideas.xml,v 1.5 2007/03/10 10:12:44 joel Exp $
     </cvs:keyword>
   </cvs:keywords>
 
@@ -630,6 +630,38 @@ be used without kernel symbols to analyze the failure mode.</p>
 <ul>
   <li>Familiarity with FreeBSD kernel debugging environment.</li>
   <li>Ability to write C code.</li>
+</ul>
+      </desc>
+    </idea>
+
+    <idea id="setproctitle" class="soc">
+      <title>Avoiding syscall overhead</title>
+
+      <desc>
+<p><strong>Technical contact</strong>: <a href="mailto:kris@FreeBSD.org">Kris Kennaway</a></p>
+
+<p>setproctitle() calls are a serious
+  performance bottleneck in a default pgsql configuration (they are
+  called at least once per query, which might be thousands of times per
+  second - I measured a performance impact of about 33% on sysbench).</p>
+
+<p>One idea for avoiding the syscall (and global sysctl lock) overhead
+  for this kind of thing would be a memory page shared between kernel
+  and userland which libc could read/write to access things like the
+  process title.  There are potentially many other data values that
+  could be optimized by a similar method.  This is presumably a well
+  established technique in other OSes.</p>
+
+<p>This project requires mentoring/review/planning with someone with
+  significant VM experience to make sure this approach
+  works properly.  Done incorrectly, this could result in fairly
+  massive security holes, performance issues (perhaps not visible in
+  simple benchmarks), etc.</p>
+
+<p><strong>Requirements</strong>:</p>
+<ul>
+  <li>Strong knowledge of C.</li>
+  <li>Understanding of kernel VM.</li>
 </ul>
       </desc>
     </idea>