Hi Sthu, Am Samstag, 15. Oktober 2011 schrieb Sthu Deus: > Thank You for Your time and answer, Henrique: > >Well, *any* issue with the disk subsystem will cause such problems to > >get several orders of magnitude worse, so yes, one must *first* make > >sure the disks are operating at the expected speed. > > How I can be sure the HDD is "operating at the expected speed"? > > >After you are sure the hardware is operating at its proper speed, you > >can start tunning the kernel and IO tasks. There is indeed such a > >thing as an IO priority per process, but due to CFQ/writeback issues, > >tuning that might not be enough. You also have to tune the kernel to > >not leave too many outstanding pages. And some filesystems are > >better than others for certain workloads. > > Let me make it clearer a bit *my* situation. > > For now I'm speaking about simple desktop environment - nothing special > w/ the HDD/FS - just SATA disk w/ EXT4 on it. I experience freezes on > any applications while, say, I copy a a big file - say just a DVD.iso - > I do not think it is normal absolutely. And as You pointed out that the
Thats a typical workload where certain kernels have lots of problems with interactivity. I think its best to use at least kernel 2.6.37. At some kernel version CFQ gained a low_latency mode which is enabled by default. Best would probably be to update to the most recent backport kernel. But as thats just a wild guess its better to first find out what the actual problem is: > discs can work not at their optimal speed (hardware issue) then I would > like to find out that. - I have read that the devices do tune > themselves pretty well for the optimal performance, though. So, how I > check that? Please do you what you do when you experience slow operation, run vmstat 1 and post the output of at least 15 lines here. Also describe what exactly you do, what stuff is running - for example which desktop environment with/or without desktop search for example - and if commands are involved post examples. Then also include at least the following: - hdparm -I /dev/sda | egrep -i "(model|transport:|likely used|DMA:)" (replace sda by whatever your drive is) - lspci -nn | egrep -i "(ide|sata)" - grep -i "model name" /proc/cpuinfo - uname -a Try to preserve formatting or use a pastebin. > >ionice from util-linux can set the process IO priority. There are > >other utilites that can also do that. > > Is it "nice" :) if I put the following > > ionice -c 2 -n 7 mc > > to /etc/rc.local > > ? Or should put it in some other place - the idea is to run all the mc > processes w/ lower IO priorities. Please do not tune before you understand whats going on. > >I couldn't readly find any up-to-date (well, up-to-2.6.32) guide on > >how to tune the VM subsystem (which controls the writeback) to refer > >you to, please look for documentation on how to mess with > >the /proc/sys/vm/* tunables. > > OK. I advise against tuning those as long as you do not understand the mechanics behind them. Ciao, -- Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7 -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/201110152023.17536.mar...@lichtvoll.de
