Marc's Public Blog - Linux Hacking


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This page has a few of my blog entries about linux, but my main linux page is here
Picture of Linus

Here is a list of older linux event reports I made before my blog was started, then the rest are below
1996/11/18-21:Linux Pavillion Comdex Fall 1996 (photos only). I've been going since then to help at the linux pavillion.
1997/11/18-21: Linux Pavillion Comdex Fall 1997 (photos only)
1998/05/28-30: Linuxexpo 1998 (photos only)
1998/11/16-20: Linux Pavillion Comdex Fall 1998 (full report)
1998/11/11: Silicon Valley Tea Party (report with pictures)
1999/02/15: Windows Refund Day (report with pictures)
1999/03/20: SVLUG KTEH night (photos only)
1999/03/01-04: LinuxWorld Expo Winter 99 (complete report with many pictures)
1999/03/31: Mozilla Party one year anniversary (photos only)
1999/05/18-22: Linuxexpo 1999 (complete report with many pictures)
1999/06/07: June 99 Balug meeting with Linus
1999/08/09-12: LinuxWorld Expo Summer 99 (complete report with many pictures)
1999/11/15-19: Linux Business Show at Comdex Fall 1999 (full report with pictures)
2000/08/14-17: LinuxWorld Expo Summer 2000 (complete report with many pictures)
2001/01/17-20: Linux.conf.au/LCA 2001 (complete report with pictures)
2001/07/25-28: OLS 2001 (photos only)
2001/08/25: Linux 10th Anniversary (report with pictures)
2001/09/27-30: LinuxWorld Expo Summer 2001 report with pictures)
2001/11/05-10: ALS 2001 (photos only)
2002/06/26-29: OLS 2002 (photos only)
2003/01/20-25: LCA 2003 (photos only)
2003/07/23-26: OLS 2003 (photos only)
2004/01/12-17: LCA 2004 (photos only)
2004/07/21-24: OLS 2004 (photos only)
2005/04/18-23: LCA 2005 (photos only)
2006/01/24-28: LCA 2006 (photos only)
2007/01/17-21: LCA 2007 (photos only)

Here is a list of all the talks I've given:

And below are my blog posts:

Table of Content for linux:

More pages: July 2002 February 2004 March 2004 November 2004 April 2005 August 2005 January 2006 July 2006 August 2007 November 2007 January 2008 October 2008 November 2008 December 2008 January 2009 May 2009 July 2009 August 2009 September 2009 November 2009 December 2009 January 2010 March 2010 April 2010 June 2010 August 2010 October 2010 January 2011 July 2011 August 2011 December 2011 January 2012 March 2012 May 2012 August 2012 December 2012 January 2013 March 2013 May 2013 September 2013 November 2013 January 2014 March 2014 April 2014 May 2014 October 2014 January 2015 March 2015 May 2015 January 2016 February 2016 June 2016 July 2016 August 2016 October 2016 January 2017 September 2017 January 2018 March 2018 December 2018 January 2019 January 2020 May 2020 January 2021 September 2021 March 2023 April 2023 December 2023 June 2024



2014/10/05 Btrfs Tips: Catch Btrfs Deadlocks
π 2014-10-05 01:01 in Btrfs, Linux

Simple cronjob to detect btrfs kernel hangs

As of 3.16, btrfs can still deadlock (it happens more frequently with older kernels).

You don't want a pile of stuck processes and having a half working server that you need to debug later. The cronjob below (a template for you to modify) will alert you when your load avarage is too high, show you which processes are blocked (could be something else than btrfs), and also show you if your swap is runnig out (btrfs has memory bugs with quotas and snapshots that can eat all your memory).

SHELL=/bin/bash

# If load average is more than MAXLA, show load average and all blocked processes # As any time show anything blocked on wait_current_trans.isra.15 (used to be a btrfs hang bug) # Also show swap if it drops below MINSWAP # We pipe into bc because shell comparison doesn't do floating point. */5 * * * * nobody MAXLA=25; MINSWAP=10; if [ $(echo "$(awk '{print $1}' < /proc/loadavg) > $MAXLA" | bc) 1 ]]; then cat /proc/loadavg; ps -eo state,pid,etime,wchan:30,args | grep W |grep -v "^[RS]" ; fi; ps -eo pid,etime,wchan:30,args | grep -q [w]ait_current_trans.isra.15; if [ $(echo "$(free | grep 'Swap' | awk '{t = $2; f = $4; print (f/t*100)}') < $MINSWAP" | bc) 1 ]]; then free; fi


More pages: July 2002 February 2004 March 2004 November 2004 April 2005 August 2005 January 2006 July 2006 August 2007 November 2007 January 2008 October 2008 November 2008 December 2008 January 2009 May 2009 July 2009 August 2009 September 2009 November 2009 December 2009 January 2010 March 2010 April 2010 June 2010 August 2010 October 2010 January 2011 July 2011 August 2011 December 2011 January 2012 March 2012 May 2012 August 2012 December 2012 January 2013 March 2013 May 2013 September 2013 November 2013 January 2014 March 2014 April 2014 May 2014 October 2014 January 2015 March 2015 May 2015 January 2016 February 2016 June 2016 July 2016 August 2016 October 2016 January 2017 September 2017 January 2018 March 2018 December 2018 January 2019 January 2020 May 2020 January 2021 September 2021 March 2023 April 2023 December 2023 June 2024

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