Messages in this thread |  | | Date | Mon, 12 Nov 2001 21:06:32 +0100 (CET) | From | Martin Josefsson <> | Subject | Re: Abysmal interactive performance on 2.4.linus |
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On Mon, 12 Nov 2001, Frank de Lange wrote:
> On a 768 MB SMP box (2x466 MHz Celeron), I see some weird problems with > interactive performance on 2.4.15pre{1,2}. A good example of this is the > following scenario: > > - copy a large file (eg. an iso image file) to a directory on the same > (reiserfs in this case) filesystem, or... > - do a filesystem comparison between a CD and the original file (with cmp > /mnt/cdrom/<filename> /mnt/reiserfs/1/data/<original_file_location>, using a > PLEXTOR Model: CD-ROM PX-40TS SCSI CD-ROM drive), > > - and THEN (while the copy or comparison runs) try any simple command (like > 'ls /mnt/reiserfs/1/data' or 'top' or anything else...). > > Response time is abysmal, a simple 'ls /some/dir' takes tens of seconds to > start. Once the command is running, performance is normal. Try this when a > cdrecord session is running and you'll get a buffer underrun. > > The box has 768 MB of RAM, 512 MB of swap. There is no significant load on the > system (according to an already running copy of top) neither before nor during > the test. Try tab-completing a command in a terminal, and that terminal freezes > for tens of seconds, usually until after the file system load has gone down. > > In a few words, heavy filesystem activity seems to wreak havoc on the system. > Not by loading the CPU (it hardly breaks out a sweat at 178% idle (SMP...)). > > Turning off swap (swapoff -a) does not change the observed behaviour. > > Anyone else seen something like this?
I have 2.4.10-ac12 here and reiserfs filesystems and I have to say that performance is terrible when doing anything diskintensive. It seems like diskscheduling is very broken for my IDE disk, or it's a reiserfs problem. maybe it pushes a _lot_ into the diskscheduling at once?
I've heard that read-ahead for IDE has been broken for a while but's fixed in -ac and in Andre Hedrick's IDE-patches.
I'm going to upgrade to a more recent kernel and see how it behaves.
/Martin
Never argue with an idiot. They drag you down to their level, then beat you with experience.
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