[This E-mail message is bottom-posting contrary to my usual custom.] On Sun, 2011-05-08 at 17:26 +0300, Gilboa Davara wrote: > On Sat, 2011-05-07 at 15:29 +0300, Omer Zak wrote: > > I have a PC with powerful processor, lots of RAM and SATA hard disk. > > Nevertheless I noticed that sometimes applications (evolution E-mail > > software and Firefox[iceweasel] Web browser) have the sluggish feel of a > > busy system (command line response time remains crisp, however, because > > the processor is 4x2 core one [4 cores, each multithreads as 2]). > > > > I run the gnome-system-monitor all the time. > > > > I notice that even when those applications feel sluggish, only one or at > > most two CPUs have high utilization, and there is plenty of free RAM (no > > swap space is used at all). > > > > Disk I/O is not monitored by gnome-system-monitor. > > So I suspect that the system is slowed down by disk I/O. I would like > > to eliminate it as a possible cause for the applications' sluggish feel. > > > > I ran smartctl tests on the hard disk, and they gave it clean bill of > > health. Therefore I/O error recovery should not be the reason for > > performance degradation. > > > > I am asking Collective Wisdom for advice about how to do: > > 1. Monitoring disk I/O load (counting I/O requests is not sufficient, as > > each request takes different time to complete due for example to disk > > head seeks or platter rotation time). > > 2. Disk scheduler fine-tuning possibilities to optimize disk I/O > > handling. > > 3. If smartctl is not sufficient to ensure that no I/O error overhead is > > incurred, how to better assess the hard disk's health? > > > > Thanks, > > --- Omer > > > > Hello Omer, > > Two questions: > > 1. Kernel version? > 2.6.38 added a very small patch that that done wonders to eliminate > foreground process scheduling issues that plagued desktop setups since > the introduction of the CFS scheduler*. (Google for +2.6.38 +group > +scheduling) > On my Fedora 14 + 2.6.38 / dual 6C Xeon workstation I can easily > watching a DVD movies while compiling the kernel and running a couple of > VM's (using qemu-kvm) in the background. Doing the same using the stock > Fedora 14 2.6.35 kernel is... err... interesting experience :)
Standard Debian Squeeze kernel: $ uname -a Linux c4 2.6.32-5-vserver-amd64 #1 SMP Mon Mar 7 23:14:47 UTC 2011 x86_64 GNU/Linux > 2. Are you sure your SATA is in AHCI mode? > (Simply type: $ find /sys/devices | grep ahci) My SATA indeed runs in non-AHCI mode. The question now is how to configure it to run in AHCI mode? According to the Wikipedia article http://en.wikipedia.org/wiki/Advanced_Host_Controller_Interface, I need to modify a BIOS setting and maybe create a new initrd image. Another source: http://www.techmetica.com/howto/sata-ahci-mode-bios-setting.-what-does-it-do/ I can handle the BIOS setting but how to check whether a new initrd image is needed, and if necessary create it? --- Omer -- Bottom posters are filthy heretics and infidels and ought to be burned on the stake after having been tarred, feathered and having rotten eggs thrown at their faces! My own blog is at http://www.zak.co.il/tddpirate/ My opinions, as expressed in this E-mail message, are mine alone. They do not represent the official policy of any organization with which I may be affiliated in any way. WARNING TO SPAMMERS: at http://www.zak.co.il/spamwarning.html _______________________________________________ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
