On Thu, Apr 1, 2010 at 3:29 PM, Rob Owens <[email protected]> wrote: > If the problem is Firefox making too many writes to the users' cache > files, as some people have speculated/demonstrated, then this isn't an > LTSP-specific problem. It should affect any system that has many > simultaneous users accessing /home, such as NFS-mounted home. I imagine > that's pretty common, so I'm surprised that this isn't a more > widely-complained-about problem.
Yes. I'll confess that I've been spending more time with the NFS dependent DRBL setups lately, and it's a problem. The only thing the teacher knows is that it's broken; impatient children just start clicking. I handle it by balancing disk arrays and I/O, using Squid when possible, changing browsers, reducing cache, and now, thanks to this thread, I'm pondering ramdisk. To standardize, I create and rsync a 'template' user to /etc/skel for new users. Some time ago I failed my way to success in scripting this with existing users. I know smarter people will have better suggestions. > > -Rob --scott > > On Thu, Apr 01, 2010 at 05:25:04PM -0700, Jordan Erickson wrote: >> Ahh, the good ole days of Firefox tackling an LTSP network like a >> football player would to an elderly woman carrying groceries home from >> the market. ;) >> >> Try these out, they helped me a bunch: >> >> https://help.ubuntu.com/community/UbuntuLTSP/Firefox3Optimize >> http://lns.wikidot.com/nsprupdate >> >> >> Cheers, >> Jordan >> >> >> >> john 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 >> > >> -- >> Jordan Erickson >> (707) 636-5678 - http://www.logicalnetworking.net >> * Please consider the environment before printing this e-mail * >> >> ------------------------------------------------------------------------------ > ------------------------------------------------------------------------------ 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
