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 :) 2. Are you sure your SATA is in AHCI mode? (Simply type: $ find /sys/devices | grep ahci) - Gilboa * At least in my case... _______________________________________________ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
