[OpenAFS-devel] AFS Performance

[Torsten Hoefler]

Hi,
we have strange performance Problems with our AFS server. We use
openafs-1.4.0-rc8 on both client and server side. Several files are
delivered extremely slow (with about 150-300 kB/s) and some can be read
with full speed of approx. 10 MB/s. This behavior is reproducable and an
upgrade from 1.3.85 did not help. The write behavior is the same,
sometimes it takes more than one minute to create a directory (the
activity on the server is 0). Are there any tools to monitor the
performance (scout and afsmonitor provide no data and indicate no
error)?

The server machine and the network cannot be the bottleneck. The server
is a dual nocona 3.4GHz with 512 MB RAM and SATA HD.
hdparm output:
---
/dev/sda:                                                                       
Timing cached reads:   3568 MB in  2.00 seconds = 1783.38 MB/sec               
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for device                                                                         
Timing buffered disk reads:  162 MB in  3.01 seconds =  53.79 MB/sec           
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for device                                                                         
---

Harddisk Performance:
---
afs ~ # time dd if=/dev/zero of=/tmp/bla bs=1M count=1024                  
1024+0 records in                                                               
1024+0 records out                                                              
                                                                                
real    0m17.175s                                                               
user    0m0.004s                                                                
sys     0m3.131s                                                                
                                                                                
afs ~ # time dd if=/tmp/bla of=/dev/null bs=1M count=1024                  
1024+0 records in                                                               
1024+0 records out                                                              
                                                                                
real    0m15.176s                                                               
user    0m0.001s                                                                
sys     0m1.420s                                                                
---

Net-Pipe Measurements from Client to Server:
---
  0:       1 bytes    654 times -->      0.06 Mbps in     127.40 usec           
  1:       2 bytes    784 times -->      0.12 Mbps in     127.47 usec           
  2:       3 bytes    784 times -->      0.18 Mbps in     126.83 usec           
  3:       4 bytes    525 times -->      0.24 Mbps in     126.94 usec           
...                                                                             
100:  786429 bytes      3 times -->     89.08 Mbps in   67355.16 usec           
101:  786432 bytes      3 times -->     89.03 Mbps in   67394.49 usec           
102:  786435 bytes      3 times -->     89.10 Mbps in   67338.00 usec           
---

The server is dedicated (only used for AFS).

Thanks for any help & kind regards,
   Torsten

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