Date: Mon, 9 Sep 2013 16:05:59 +0000 (UTC) From: Gabor Pali <pgj@FreeBSD.org> To: doc-committers@freebsd.org, svn-doc-all@freebsd.org, svn-doc-head@freebsd.org Subject: svn commit: r42634 - head/en_US.ISO8859-1/htdocs/news/status Message-ID: <201309091605.r89G5xcv039419@svn.freebsd.org>
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Author: pgj Date: Mon Sep 9 16:05:59 2013 New Revision: 42634 URL: http://svnweb.freebsd.org/changeset/doc/42634 Log: - Add Q3 reports on static code analysis [1] and CAM locking [2] Submitted by: uqs [1], mav [2] Modified: head/en_US.ISO8859-1/htdocs/news/status/report-2013-07-2013-09.xml Modified: head/en_US.ISO8859-1/htdocs/news/status/report-2013-07-2013-09.xml ============================================================================== --- head/en_US.ISO8859-1/htdocs/news/status/report-2013-07-2013-09.xml Mon Sep 9 14:54:33 2013 (r42633) +++ head/en_US.ISO8859-1/htdocs/news/status/report-2013-07-2013-09.xml Mon Sep 9 16:05:59 2013 (r42634) @@ -19,7 +19,7 @@ <!-- XXX: keep updating the number of entries --> <p>Thanks to all the reporters for the excellent work! This report - contains 1 entries and we hope you enjoy reading it.</p> + contains 3 entries and we hope you enjoy reading it.</p> <!-- XXX: set date for the next set of submissions --> <p>The deadline for submissions covering between October and @@ -27,6 +27,12 @@ </section> <category> + <name>proj</name> + + <description>Projects</description> + </category> + + <category> <name>kern</name> <description>Kernel</description> @@ -60,4 +66,126 @@ framework and <tt>crypto(4)</tt>.</p> </body> </project> + + <project cat='proj'> + <title>Static Code Analysis</title> + + <contact> + <person> + <name> + <given>Ulrich</given> + <common>Spoerlein</common> + </name> + <email>uqs@FreeBSD.org</email> + </person> + </contact> + + <links> + <url href="http://scan.coverity.com/">Coverity Scan</url> + <url href="http://scan.freebsd.your.org/">Clang Static Analyzer Scan for &os;</url> + <url href="http://clang-analyzer.llvm.org/">Clang Static Analyzer Home Page</url> + </links> + + <body> + <p>With our own (old and unstable) instance of Coverity Prevent + gone, we have now fully transitioned to the Scan project run by + Coverity (see links), which Open Source projects can use to + learn about possible defects in their source code.</p> + + <p>We also continue to run our code base through the Static + Analyzer that is shipped with Clang/LLVM. It cannot track the + state of the code over time, but has the benefit that everyone + can use it without any special setup. See the home page at the + links section for more information on the Clang Static Analyzer + project in general, and head over to the &os; Clang Static + Analyzer Scan page (see links) to see those possible defects (no + signup required).</p> + + <p>We are looking for a co-admin for both of these projects to + increase the bus-factor and the chance of survival for these + services. Fame and fortune await!</p> + </body> + + <help> + <task>Maybe turn on email reports for new defects to the internal + list of &os; developers.</task> + + <task>Find co-admin.</task> + + <task>Fix the defects reported by Coverity and Clang.</task> + </help> + </project> + + <project cat='kern'> + <title>GEOM Direct Dispatch and Fine-Grained CAM Locking</title> + + <contact> + <person> + <name> + <given>Alexander</given> + <common>Motin</common> + </name> + <email>mav@FreeBSD.org</email> + </person> + </contact> + + <links> + <url href="http://svnweb.freebsd.org/base/projects/camlock/">Project SVN branch</url> + <url href="http://people.freebsd.org/~mav/camlock_patches/">Project patches</url> + </links> + + <body> + <p>Last year's high-performance storage vendors reported + performance bottleneck in &os; block storage subsystem, limiting + peak performance around 300-500K IOPS. While that is still more + then enough for average systems, detailed investigation has + shown number of places that require radical improvement. + Unmapped I/O support implemented early this year already + improved I/O performance by about 30% and moved more accents + toward GEOM and CAM subsystems scalability. Fixing these issues + was the goal of this project.</p> + + <p>The existing GEOM design assumed the most of I/O handling to be + done by only two kernel threads (<tt>g_up()</tt> and + <tt>g_down()</tt>). That simplified locking in some cases, but + limited potential SMP scalability and created additional + scheduler overhead. This project introduces concept of direct + I/O dispatch into GEOM for cases where it is know to be safe and + efficient. That implies marking some of GEOM consumers and + providers with one or two new flags, declaring situations when + direct function call can be used instead of normal request + queuing. That allows to avoid any context switches inside GEOM + for the most widely used topologies, simultaneously processing + multiple I/Os from multiple calling threads.</p> + + <p>Having GEOM passing through multiple concurrent calls down to + the underlying layers exposed major lock congestion in CAM. In + existing CAM design all devices connected to the same ATA/SCSI + controller are sharing single lock, which can be quite busy due + to multiple controller hardware accesses and/or code logic. + Experiments have shown that applying only above GEOM direct + dispatch changes burns up to 60% of system CPU time or even more + in attempts to obtain these locks by multiple callers, killing + any benefits of GEOM direct dispatch. To overcome that new + fine-grained CAM locking design was implemented. It implies + splitting big per-SIM locks into several smaller ones: per-LUN + locks, per-bus locks, queue locks, etc. After these changes + remaining per-SIM lock protects only controller driver + internals, reducing lock congestion down to acceptable level and + allowing to keep compatibility with existing drivers.</p> + + <p>Together GEOM and CAM changes twice increase peak I/O rate, + reaching up to 1,000,000 IOPS on contemporary hardware.</p> + + <p>The changes were tested by number of people and are going to be + committed into &os; <tt>head</tt> and merged to + <tt>stable/10</tt> after the end of &os; 10.0 release cycle.</p> + + <p>The project is sponsored by iXsystems, Inc.</p> + </body> + + <help> + <task>More reviews, more stability and performance tests.</task> + </help> + </project> </report>
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