On 06/14/2012 12:08 PM, Bernhard Voelker wrote:
On 06/14/2012 02:11 AM, Florian Gleixner wrote:
To make the problem clearer:
- the initial problem occured by using cp or mv - not dd. I use dd only to prove that the local disk is not part of the problem by reading from /dev/zero - the system seems to freeze totally for the time of the transfer. The transfer does not slow down, but i cannot use firefox for example. In extreme cases the mouse movements freeze! But i can login via ssh, so the system still works, except processes that use /proc (seen from strace)
I tried to reproduce the problem, but instead of using eth0, I used the lo interface - which avoids potential NIC driver problems.
$ mkdir /tmp/test $ truncate -s10G /tmp/test/file $ du -h /tmp/test/file ; du -h --apparent-size /tmp/test/file 0 /tmp/test/file 10G /tmp/test/file $ echo '/tmp/test 127.0.0.1(ro,no_subtree_check)' >> /etc/exports $ exportfs -av exporting 127.0.0.1:/tmp/test $ mount -t nfs 127.0.0.1:/tmp/test /mnt $ ifconfig lo | grep RX\ bytes RX bytes:21623669265 (20621.9 Mb) TX bytes:21623669265 (20621.9 Mb) $ dd if=/mnt/file of=/dev/null 20971520+0 records in 20971520+0 records out 10737418240 bytes (11 GB) copied, 24.6555 s, 435 MB/s $ ifconfig lo | grep RX\ bytes RX bytes:32446807849 (30943.6 Mb) TX bytes:32446807849 (30943.6 Mb)
You see the 10G data has really been transferred, but no freeze happened. My system seems to use NFS version 3.
Can you reproduce this?
Have a nice day, Berny
Nice idea to avoid network related issues, but the problem is not reading from NFS but writing to it. I did a write-test to a localhost nfs server yesterday and it freezed after writing ~150MB. I could not recover from the freeze and after a reboot i could not reproduce the issue. I'll do further tests if the weather will let me :-) Thanks!