hi all
why is it that Linux 'hangs' while doing heavy I/O operations (such as dd)
to (and perhaps from?) ext2 file systems? I can't see the same behaivour
when using other file systems, such as ReiserFS
roy
--
Roy Sigurd Karlsbakk, MCSE, MCNE, CLS, LCA
Computers are like air conditioners.
They stop working when you open Windows.
Roy Sigurd Karlsbakk wrote:
>
> hi all
>
> why is it that Linux 'hangs' while doing heavy I/O operations (such as dd)
> to (and perhaps from?) ext2 file systems? I can't see the same behaivour
> when using other file systems, such as ReiserFS
>
A partial fix for this went into 2.4.17-pre2. What kernel are you
using?
For how long does it "hang"? What exactly are you doing when it
occurs?
Is your disk system well-tuned? What throughput do you get with
`hdparm -t /dev/hdXX'?
It surprises me that resierfs behaves differently...
-
> > why is it that Linux 'hangs' while doing heavy I/O operations (such as
dd)
> > to (and perhaps from?) ext2 file systems? I can't see the same behaivour
> > when using other file systems, such as ReiserFS
> >
>
> A partial fix for this went into 2.4.17-pre2. What kernel are you
> using?
i have always had with problem normally during disk writes.
currently on 2.4.x-14 + 2.4.16
> For how long does it "hang"? What exactly are you doing when it
> occurs?
its not that it hangs but it gets extremely laggy eg 2/3 seconds pause
for keyboard input to appear on a console.
> Is your disk system well-tuned? What throughput do you get with
> `hdparm -t /dev/hdXX'?
i have tuned with hdparm as much as i can. but i cannot tune the
VM because the files in /proc/sys/vm do not seem to make any difference
to the system at all and the documents dont seem to be correct inn
procfs.txt
if docs are wrong for a kernel version would it not be better to either say
they are wrong
or remove them alll together. but i assume this is todo with the latest VM
change.
are there going to be new documents for these files ?
James
James Stevenson wrote:
>
> > > why is it that Linux 'hangs' while doing heavy I/O operations (such as
> dd)
> > > to (and perhaps from?) ext2 file systems? I can't see the same behaivour
> > > when using other file systems, such as ReiserFS
> > >
> >
> > A partial fix for this went into 2.4.17-pre2. What kernel are you
> > using?
>
> i have always had with problem normally during disk writes.
> currently on 2.4.x-14 + 2.4.16
Please try 2.4.17-pre2 or later.
> > For how long does it "hang"? What exactly are you doing when it
> > occurs?
>
> its not that it hangs but it gets extremely laggy eg 2/3 seconds pause
> for keyboard input to appear on a console.
Your app got paged out, and the enormous read latencies in 2.4.16
caused it to remain there.
> >
> > > > why is it that Linux 'hangs' while doing heavy I/O operations (such
as
> > dd)
> > > > to (and perhaps from?) ext2 file systems? I can't see the same
behaivour
> > > > when using other file systems, such as ReiserFS
> > > >
> > >
> > > A partial fix for this went into 2.4.17-pre2. What kernel are you
> > > using?
> >
> > i have always had with problem normally during disk writes.
> > currently on 2.4.x-14 + 2.4.16
>
> Please try 2.4.17-pre2 or later.
>
ok i should have some time to try that at the weekend.
> > its not that it hangs but it gets extremely laggy eg 2/3 seconds pause
> > for keyboard input to appear on a console.
>
> Your app got paged out, and the enormous read latencies in 2.4.16
> caused it to remain there.
why would it have been paged out there was loads of free
ram. there is 192MB in the machine and no X windows or
anything and the app was bash and there are not many other processes.
James