[Ed Boraas CC-ed, probably this is of interest for Debian people.] Corey G. writes: > My Problem and Solution to Bad Performance Using Debian Woody and ReiserFS > -------------------------------------------------------------------------- > > My first three attempts with ReiserFS and Woody were quite dismal. Not > with the installation, but with performance. I was quite literally pulling > hair out of my head because ReiserFS on Mandrake 9 performs remarkably > in my opinion. Why would it work so awful with Debian 3.0? Note: By > design, the default boot disks for Debian 3.0 do not contain ReiserFS > support. In order to install ReiserFS during an initial installation, > you must download the BF2.4 disks which have "experimental drivers". I > have seen many comments on the web wondering why Debian still thinks > Reiser is experimental. It must be driven by the ultra conservatism of > Debian. Regardless, ReiserFS is available for Debian Woody. > > > Addressing the Problem: > ----------------------- > My first assumption was the kernel, so I upgraded to 2.4.19. No such > luck. Untarring Mozilla took 3m24s on an Athlon 800mzh with 1GB RAM. > The same test took 6 seconds on Mandrake on the same system. After > digging into the problem I finally came to the conclusion that Mandrake, > and probably other distributions, are tuning the hard drives > during installation or boot. I dug around and found some rather safe > settings to implement using "hdparm". After applying the changes below, > my Debian system came to life. Now I could untar at the speed of light > and still use my mouse at the same time. > > So, for whatever reason, Debian has chosen to be quite conservative > with assumptions on hard drive tuning. I will admit that some of the > parameters I tried locked up my machine. However, even the more > conservative settings work very nice. My concern here is that > other individuals are certainly going to experience this problem with Debian > besides myself. Another colleague here said he went back to ext2 because > the performance was horrible with ReiserFS on Debian. Unfortunately, > this individual refuses to try other distributions so he never had > anything to compare. Had I not seen the incredible performance on > Mandrake, I would have assumed that ReiserFS was a very slow filesystem. > > To prove my theory about Mandrake pre-tuning the drives during boot, I had > a colleague run hdparm on his Mandrake 9 installation. Here is the output: > > > /dev/hda: > multcount = 16 (on) > IO_support = 0 (default 16-bit) > unmaskirq = 0 (off) > using_dma = 1 (on) > keepsettings = 0 (off) > readonly = 0 (off) > readahead = 8 (on) > geometry = 1292/240/63, sectors = 19541088, start = 0 > > > These settins were NOT on by default with Debian. The most important > (I know this from testing) is "using_dma". After turning this on, things > really start to move.
Probably this is because not using DMA increases CPU usage and reiserfs already loads CPU significantly. > > Here are my current settings with Debian: > > /dev/hda: > multcount = 16 (on) > I/O support = 1 (32-bit) > unmaskirq = 1 (on) > using_dma = 1 (on) > keepsettings = 0 (off) > nowerr = 0 (off) > readonly = 0 (off) > readahead = 8 (on) > geometry = 4866/255/63, sectors = 78177792, start = 0 > busstate = 1 (on) > > > I simply added a start script to /etc/init.d with the following: > > #!/bin/sh > > hdparm -m 16 -d 1 -u 1 -c 1 /dev/hda > You can also use -X option of hdparm. Thank you for your research. > > -- > Best Regards, > Corey G. > Nikita.
