On Fri, 24 Oct 2003, Jeff Dike wrote:
> linux@xxxxxxxxxxxx said:
> > I have seen some posts to this list that expanding the on disk usage
> > of a sparse file can be time consuming. But the strange part of this
> > problem is that on one machine, these lockups are less than a second
> > (a few hundred milliseconds), and on the other machine they are
> > several seconds (10-40 seconds). The former machine is a P2-400 w/
> > 256MB RAM, and 30GB IDE HD. The latter machine is a Athlon 1.4GHz w/
> > 1GB RAM, and 3x36GB Ultra160 RAID5 (software) SCSI array. So, yes, the
> > far faster machine is showing these lockups much worse than the slower
> > machine. :(
>
> Is it just the UML that's wedged, or the whole box?
Just the UML that is wedged, the host is just fine, as if nothing
out of the ordinary was going on.
> If it's really many 10s of seconds, then some vmstat data would be
> interesting. Start it during this period and let it run for a little
> afterwards so that the difference is apparent.
Okay, attached are four files from my two different machines:
vmstat-slow.host.log :: Host 'vmstat 1' log on the P2.
vmstat-slow.uml.log :: UML 'vmstat 1' log on the P2.
vmstat-fast.host.log :: Host 'vmstat 1' log on the Athlon.
vmstat-fast.uml.log :: UML 'vmstat 1' log on the Athlon.
For each pair of files, vmstat was started on both the host and UML at
about the same time and allowed to run for ~30 seconds. Then a copy via
netcat and afio of ~200MB of PDF files over a 100mbit network from a
separate machine (not the UML host) to the UML was started. I am using
bridging and tuntap for network access. The filesystem image being used is
a sparse file, and it expanded by at least 100MB during the file copy. The
only difference I can see between the two UML instances is that on the P2
the allocated memory for the UML is 64MB, while on the Athlon it is 128MB.
The vmstat-fast.uml.log is quite interesting, as it is much, much
shorter than the vmstat-fast.host.log. The reason it is shorter is due to
the UML system being wedged for much of the copy. The P2 took only a
minute to do this transfer, while the Athlon took nearly five minutes.
Hopefully these logs are of use. If there are any other tests I
can run, please let know. Thanks!
---------------------------------------------------------------------------
| "For to me to live is Christ, and to die is gain." |
| --- Philippians 1:21 (KJV) |
---------------------------------------------------------------------------
| Ryan Kirkpatrick | Boulder, Colorado | http://www.rkirkpat.net/ |
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vmstat-fast.host.log.gz
Description: Binary data
vmstat-fast.uml.log.gz
Description: Binary data
vmstat-slow.host.log.gz
Description: Binary data
vmstat-slow.uml.log.gz
Description: Binary data
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