disk throughput down in 2.5.8

disk throughput down in 2.5.8

Post by Mikael Pettersso » Sat, 20 Apr 2002 08:40:12



Is it just me or is disk I/O throughput way down in 2.5.8?

I was preparing to build 2.4.19-pre7 on a box running 2.5.8,
when I noticed that 'tar zxvf' on the kernel tarball seemed
slow and jerky. So I ran

        cd /tmp; time tar zxf /path/to/linux-2.5.8.tar.gz

on several boxes(*), comparing 2.4.19-pre7 with 2.5.8.

On the older boxes (2 PentiumIIs and one K6-III), 2.5.8 was slower
by factors of 2.3-4.5. A P4 with an IBM 60GXP "only" suffered a
40% slowdown.

/Mikael

(*) Standard Intel chipset PCs, IDE disks, ext2 file systems,
newly booted, idle, etc.
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disk throughput down in 2.5.8

Post by Andrew Morto » Sat, 20 Apr 2002 10:40:06



> Is it just me or is disk I/O throughput way down in 2.5.8?

> I was preparing to build 2.4.19-pre7 on a box running 2.5.8,
> when I noticed that 'tar zxvf' on the kernel tarball seemed
> slow and jerky. So I ran

>         cd /tmp; time tar zxf /path/to/linux-2.5.8.tar.gz

> on several boxes(*), comparing 2.4.19-pre7 with 2.5.8.

> On the older boxes (2 PentiumIIs and one K6-III), 2.5.8 was slower
> by factors of 2.3-4.5. A P4 with an IBM 60GXP "only" suffered a
> 40% slowdown.

I can't say that it's happening here.  The time to untar
and sync a kernel tarball from /dev/sdb6 to /dev/sdb5:

2.4.19-pre4:
~/doit  6.55s user 3.69s system 53% cpu 19.225 total
2.4.19-pre7
~/doit  6.82s user 3.29s system 53% cpu 18.811 total
2.5.8:
~/doit  6.32s user 3.52s system 56% cpu 17.401 total

So 2.5.8 is a little quicker.  Note that this time includes
"sync".  2.4.19-recent has more intelligent write-behind
than other kernels, and if you don't include the /bin/sync
time, you actually miss out on timing a lot of the I/O.
Which is a good feature in 2.4, but it only goes so far.

dbench throughput is down the tubes in 2.5.8 - partly because
the kernel is starting too many pdflush threads, and partly
because I (had to) take out the bit of code where bdflush
waits on I/O completion before looking for another wakeup.
That would be a waste of pdflush resources.  It needs to
be addressed by other means, but not with the buffer LRUs.

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1. determine throughput from LAN to Internet, Durchsatz vom LAN ins Internet berechnen

Hi,

Does anyone have a program (or a link to a program) which determines
(under LINUX) how much a single computer in a network
downloads/uploads to/from the intenet?
In particular:
I have a linux-router connected to the internet (ppp0) and also
connected to a local LAN(ethX). Now I want to know, which of the Nodes
(connected to the internal LAN) consume how much throughput (in MB or
KB) to the Internet (extern WAN). Upload and download. Until now all
is done via 'iptables', working (masquerading).

THX for any help.

Hallo,

Kennt jemand ein Programm (oder den Link zu einem Programm) welches
unter LINUX feststellt, welcher lokale Rechner wie viel vom Internet
ladet/uplodaet?
Genau gesagt:
Ich habe einen LUNUX-router, welcher zum Internet (ppp0) als auch zum
internen LAN (eht0) verbunden ist. Jetzt m?chte ich wissen, wie viel
jeder einzelne Rechner im LAN vom Internet ladet bzw. wie viel jeder
einzelne Rechner ins Internet uploadet. Bis jetz funktioniert alles
ber die IPTABLES und es funktioniert (MASQUERADING).

Danke fr jede Hilfe.

Cheers, Kuge

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