Messages in this thread | | | Date | Sat, 22 May 1999 19:34:02 +0200 | From | Thierry Danis <> | Subject | Slow NFS reading with multiple clients |
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Hello,
I am resending that post since it has had no echo and seemed to hide some problem.
I have installed the RH 6.0 on a Linux NFS server and updated the kernel to 2.2.7-ac1.
I am testing NFS with iozone.
The NFS server is doing rather well with one client (6,8Mo/s with a 2.2.{6,7}-ac1 Linux client, 7,3 Mo/s with a FreeBSD client for writing, 4,5 Mo/s during reading for Linux, 4,8 Mo/s for FreeBSD).
Unfortunately, when I run two clients at the same time, reading performance drops drastically : 700 Ko/s each. During rereading, the load of the server climbs between 4 and 5. With 1 client, the load during reading ist around 0,20.
When I run two iozones locally on the server, I get 3,5 Mo/s on each iozone (ie, the global rate is around 7 Mo/s, which is consistent).
So, to summary :
1) 1 NFS client : ~ 7 Mo/s writing, 5 Mo/s reading 2) 2 NFS clients: ~ 7 Mo/s writing, 1,5 Mo/s reading (cumulated : BAD)
3) 1 local client : ~ 9 Mo/s writing, 7 Mo/s reading 4) 2 local clients : ~ 9 Mo/s writing, 7 Mo/s reading. (cumulated : OK)
Where can the problem (1,5 Mo/s) be ?
I tried with 2.2.6-ac1 on the server, without any change.
No process seems to eat that much CPU :
> 7:32pm up 18 min, 1 user, load average: 6.95, 3.91, 2.09 > 47 processes: 44 sleeping, 3 running, 0 zombie, 0 stopped > CPU states: 0.1% user, 1.7% system, 0.0% nice, 98.0% idle > Mem: 63392K av, 61900K used, 1492K free, 2536K shrd, 1320K buff > Swap: 120480K av, 4372K used, 116108K free 56472K cached > > PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND > 485 root 2 0 0 0 0 DW 0 0.3 0.0 0:10 nfsd > 486 root 1 0 0 0 0 DW 0 0.3 0.0 0:09 nfsd > 973 danis 2 0 488 448 336 R 0 0.3 0.7 0:04 top > 483 root 1 0 0 0 0 DW 0 0.1 0.0 0:10 nfsd > 484 root 1 0 0 0 0 DW 0 0.1 0.0 0:10 nfsd > 487 root 2 0 0 0 0 DW 0 0.1 0.0 0:10 nfsd > 488 root 1 0 0 0 0 DW 0 0.1 0.0 0:09 nfsd ...
A +, -- Thierry Danis
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