On Thu, Apr 1, 2010 at 11:21 AM, john <[email protected]> wrote: > Hi all, > > As a follow up to my previous post. I did some testing and have come > to the conclusion that firefox is indeed at the heart of my problem > re: high I/O wait times. See below. > > On Wed, Mar 31, 2010 at 6:39 PM, john <[email protected]> wrote: > >> Oh, heck, I'll throw out another thing :-) >> >> I was surprised to see that there was so much disk write activity. I >> am trying to figure out what is getting written where. I found a tool >> called IOTOP that should correlate disk i/o to particular apps. >> Unfortunately it uses some kernel hooks that aren't supported by >> Ubuntu kernels so i am in the process of compiling an ubuntu kernel >> with the proper stuff included. > > So I compiled a custom kernel by copying my .config and following directions > here https://help.ubuntu.com/community/Kernel/Compile > > I turned enabled I/O accounting so that I could use IOTOP > http://guichaz.free.fr/iotop/ > > CONFIG_TASK_IO_ACCOUNTING=y > > compiled the kernel and rebooted. > > IOTOP has a number of interesting features, including the ability to > show all processes, all threads, only active process/threads, > cumulative or real-time disk I/O etc. Running IOTOP while opening > web pages in firefox, browsing, watching youtube etc, showed my that > firefox does a LOT of disk writes and very few reads. Here's some > sample output in with the "cumulative" switch turned on > > # iotop -a -P > > total DISK READ: 0.00 B/s | Total DISK WRITE: 0.00 B/s > PID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND > 4423 be/3 root 12.00 K 1984.00 K 0.00 % 0.13 % [kjournald] > 2581 be/3 root 0.00 B 636.00 K 0.00 % 0.03 % [kjournald] > 5099 be/3 ntp 12.00 K 4.00 K 0.00 % 0.00 % ntpd -p > /var/run/ntpd.pid -u 115:127 -g > 10442 be/4 john 8.00 K 0.00 B 0.00 % 0.00 % gnome-terminal > 7207 be/4 john 16.00 K 0.00 B 0.00 % 0.00 % > gnome-panel --sm-client-id default1 > 10688 be/4 john 4.00 K 17.20 M 0.00 % 0.00 % firefox-bin > 7172 be/4 john 0.00 B 336.00 K 0.00 % 0.00 % gconfd-2 11 > 5005 be/4 syslog 0.00 B 52.00 K 0.00 % 0.00 % syslogd -u syslog > 5623 be/4 root 0.00 B 180.00 K 0.00 % 0.00 % winbindd > > In 10 minutes of futzing about firefox wrote 17.2 M to disk and read > off 4K. All the writing apparently happens in the users ./mozilla > directory. Indeed of the 47Gigs used on my disk 26Gigs (55%) are given > over to my 570 users firefox profiles (eg ~45 M per user). > > The space isn't a problem, but I am really beginning to think all of > that disk activity is really hurting our performance. I > often feel like some of the best aspects of LTSP are nullified by > Firefox's affect on the multi-user environment. At the same time I > like firefox as a web-browser. I would love to find a way to make > firefox feel like less of a liability, perhaps pushing /home to a > faster disk will do that. I think Firefox's problems under LTSP really > color our users perception of the usefulness of LTSP/ubuntu. Perhaps > I just don't know how to configure Firefox correctly... > > I have followed > https://help.ubuntu.com/community/UbuntuLTSP/Firefox3Optimize and I > hope that it will make a difference. I am also going to mount /home on > a separate disk either under raid 0 or 10 and/or perhaps buy a SAS or > solid state disk. I am still mulling that one. > > I'm still interested in folks ideas about the "fastest" approach to > take re: disk writes, and especially ideas about taming firefox under > LTSP. > > Thanks to all for your ideas! > > John > > ------------------------------------------------------------------------------ > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. Speed compiling, find bugs > proactively, and fine-tune applications for parallel performance. > See why Intel Parallel Studio got high marks during beta. > http://p.sf.net/sfu/intel-sw-dev > _____________________________________________________________________ > Ltsp-discuss mailing list. To un-subscribe, or change prefs, goto: > https://lists.sourceforge.net/lists/listinfo/ltsp-discuss > For additional LTSP help, try #ltsp channel on irc.freenode.net >
------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _____________________________________________________________________ Ltsp-discuss mailing list. To un-subscribe, or change prefs, goto: https://lists.sourceforge.net/lists/listinfo/ltsp-discuss For additional LTSP help, try #ltsp channel on irc.freenode.net
