Ext3 users - Jan 2003 - Write to ext3 fs -> kjournald goes bananas

Hello,

we have just observed a rather annoying behavior one of our servers.
Specifically, when writing data to a file on an ext3fs filesystem at
around 1.5 MB/sec, network connectivity suddently started to show
signs of lag.

The ping would spike up to ~1 second every 5 seconds or so. This affects
the server in question and all hosts routing traffic through it (i.e.,
it's not a userland-only problem).

When this happens, the load skyrockets (> 10 on an otherwise mostly idle
server) and kjournald can be seen consuming CPU cycles like mad.

When the write to the file is paused, the problem immediately goes away,
and then resurfaces.

This is on a 2.4.19 kernel.

Is this a known problem with ext3fs? Granted, we cannot be sure ext3fs
is involved, but it's a pretty good bet it is.

-- 
/ Peter Schuller, InfiDyne Technologies HB

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Peter Schuller <peter.schuller@infidyne.com>
wrote:
>
> Hello,
> 
> we have just observed a rather annoying behavior one of our servers.
> Specifically, when writing data to a file on an ext3fs filesystem at
> around 1.5 MB/sec, network connectivity suddently started to show
> signs of lag.
> 
> The ping would spike up to ~1 second every 5 seconds or so. This affects
> the server in question and all hosts routing traffic through it (i.e.,
> it's not a userland-only problem).
> 
> When this happens, the load skyrockets (> 10 on an otherwise mostly idle
> server) and kjournald can be seen consuming CPU cycles like mad.
> 
Usually, this sort of thing is caused by an IDE subsystem which is not
running in DMA mode.

You can use `hdparm /dev/hda' to display the current DMA setting.