Coda File System

Re: write speed

From: Vojtech Moravek <vojtech.moravek_at_cz.tiscali.com>
Date: 31 Jan 2003 10:36:29 +0100
Hi Jan,

thaks for reply, but still thinking that problem is anywhere in kernel.
For eliminate network problems and others bugs describe configuration on
problematic computer.

 There is no network operations only write on the same computer.

I can send more information from /proc.
IBM eServer 345, 2x XEON 2Ghz, 2GB RAM


If you have more ideas..will be good soud for me :)

Vojtech


Only what  change is kernel:


-------------2.4.18-14smp-------

uname -rva
Linux sklad1 2.4.18-14smp #1 SMP Wed Sep 4 12:34:47 EDT 2002 i686 i686
i386 GNU/Linux


time dd if=/dev/zero of=/coda/test bs=1024 count=1024
1024+0 records in
1024+0 records out

real    0m40.474s
user    0m0.002s
sys     0m0.018s

Here is vmstat... when is "1" in "b" column dd command is working.

[root_at_sklad1 root]# vmstat 1
   procs                      memory    swap          io    
system         cpu
 r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us 
sy  id
 0  0  0      0 1641284   7408 204052   0   0    60     7  131    12  
0   0  99
 0  0  0      0 1641284   7408 204052   0   0     0     0  517     6  
0   0 100
 0  0  0      0 1641284   7408 204052   0   0     0     0  517     8  
0   0 100
 0  0  0      0 1641284   7416 204052   0   0     0    89  526    21  
0   0 100
 0  1  0      0 1640828   7424 203032   0   0     0  1075  541   136  
0   1  99
 0  1  0      0 1640828   7424 203036   0   0     0     0  520    30  
0   0 100
 0  1  0      0 1640828   7424 203056   0   0     0     0  519    90  
0   0 100
 0  1  0      0 1640828   7428 203084   0   0     0     0  521   126  
0   0 100
 0  1  0      0 1640828   7448 203108   0   0     0   180  524   110  
0   0 100
 0  1  0      0 1640828   7448 203132   0   0     0     0  523   104  
0   0 100
 0  1  0      0 1640828   7448 203164   0   0     0     0  516   116  
0   0 100
 0  1  0      0 1640828   7448 203188   0   0     0     0  517   178  
0   0 100
 0  1  0      0 1640828   7448 203220   0   0     0     0  523   128  
0   0 100
 0  1  0      0 1640828   7464 203252   0   0     0   248  522   138  
0   0 100
 0  1  0      0 1640828   7464 203276   0   0     0     0  521    94  
0   0 100
 0  1  0      0 1640828   7464 203300   0   0     0     0  518    90  
0   0 100
 0  1  0      0 1640828   7464 203340   0   0     0     0  523   146  
0   0 100
 0  1  0      0 1640828   7464 203364   0   0     0     0  523    94  
0   0 100
 0  1  0      0 1640828   7480 203388   0   0     0   216  523   114  
0   0 100
 0  1  0      0 1640828   7480 203420   0   0     0    33  530   152  
0   0 100
 0  1  0      0 1640828   7480 203452   0   0     0     0  516   126  
0   0 100
 0  1  0      0 1640828   7480 203484   0   0     0     0  522   122  
0   0 100
 0  1  0      0 1640828   7480 203516   0   0     0     0  519   126  
0   0 100
 0  1  0      0 1640828   7496 203540   0   0     0   152  526   120  
0   0 100
 0  1  0      0 1640828   7496 203564   0   0     0     0  527   106  
0   0 100
 0  1  0      0 1640828   7496 203596   0   0     0     0  527   128  
0   0 100
 0  1  0      0 1640828   7496 203620   0   0     0     0  524    92  
0   0 100
 0  1  0      0 1640828   7496 203644   0   0     0     0  520    90  
0   0 100
 0  1  0      0 1640828   7512 203676   0   0     0   176  527   150  
0   0 100
 0  1  0      0 1640828   7512 203708   0   0     0     0  522   126  
0   0 100
 0  1  0      0 1640828   7512 203732   0   0     0     0  523    94  
0   0 100
 0  1  0      0 1640828   7512 203764   0   0     0     0  519   124  
0   0 100
 0  1  0      0 1640828   7512 203788   0   0     0     0  520    92  
0   0 100
 0  1  0      0 1640828   7528 203812   0   0     0   184  532   110  
0   0 100
 0  1  0      0 1640828   7528 203852   0   0     0     0  523   166  
0   0 100
 0  1  0      0 1640828   7528 203884   0   0     0     0  521   124  
0   0 100
 0  1  0      0 1640828   7528 203916   0   0     0     0  524   118  
0   0 100
 0  1  0      0 1640828   7528 203948   0   0     0     0  522   110  
0   0 100
 0  1  0      0 1640828   7544 203972   0   0     0   192  524   107  
0   0 100
 0  1  0      0 1640828   7544 203996   0   0     0     0  518    98  
0   0 100
 0  1  0      0 1640828   7544 204032   0   0     0     0  521   132  
0   0 100
 0  1  0      0 1640828   7544 204032   0   0     0     0  525   110  
0   0 100
 0  1  0      0 1640828   7544 204036   0   0     0     0  526    30  
0   0 100
 0  1  0      0 1640828   7560 204040   0   0     0   156  530    46  
0   0 100
 0  1  0      0 1640824   7560 204048   0   0     0     0  519    26  
0   0 100
 0  0  0      0 1640828   7560 204052   0   0     0    53  530    36  
0   0 100
 0  0  0      0 1640828   7560 204052   0   0     0     0  517     6  
0   0 100
 0  0  0      0 1640828   7560 204052   0   0     0     0  519    10  
0   0 100



-------------2.4.18-14-------
uname -rva
Linux sklad1 2.4.18-14 #1 Wed Sep 4 13:35:50 EDT 2002 i686 i686 i386
GNU/Linux


 time dd if=/dev/zero of=/coda/test bs=1024 count=1024
1024+0 records in
1024+0 records out

real    0m0.155s
user    0m0.002s
sys     0m0.004s

Write was when "b" have "2"

vmstat 1
   procs                      memory    swap          io    
system         cpu
 r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us 
sy  id
 0  0  0      0 1645440   5972 204520   0   0   612    59  543    91  
1   3  97
 0  0  0      0 1645440   5972 204520   0   0     0     0  520    10  
0   0 100
 0  0  0      0 1645440   5972 204520   0   0     0     0  519     7  
0   0 100
 0  0  0      0 1645440   5972 204520   0   0     0     0  518    11  
0   0 100
 0  2  0      0 1645608   5972 203496   0   0     0  1032  528    38  
0   1  99
 0  0  0      0 1645336   6000 204524   0   0     0  1201  553  2106  
3   2  95
 0  0  0      0 1645336   6000 204524   0   0     0     0  522     7  
0   0 100
 0  0  0      0 1645336   6000 204524   0   0     0     0  524     7  
0   0 100
 0  0  0      0 1645336   6000 204524   0   0     0     0  516     7  
0   0 100


On Čt, 2003-01-30 at 21:02, Jan Harkes wrote:

> On Thu, Jan 30, 2003 at 03:39:44PM +0100, Vojtech Moravek wrote:
> > Yesteraday i wrote some problems with slow write operations. I made some
> > tests and results is:
> > 
> > When coda run on computers which have only one cpu. Everything is cool.
> > When is CODA installed on twoCPUs computer I have problem with write
> > operations.. more describes are bellow:
> 
> It must be some timing issue. When I write a 1MB file in connected mode
> to 2 servers (servers are PII-200, client is PIII-1000)
> 
>     jaharkes_at_ravel$ time dd if=/dev/zero of=foo bs=1024 count=1024
>     1024+0 records in
>     1024+0 records out
> 
>     real    0m0.760s
>     user    0m0.000s
>     sys     0m0.010s
> 
> 
> When I do the same operation in write-disconnected mode it completes
> almost instantaneously.
> 
>     jaharkes_at_ravel$ cfs wd .
>     jaharkes_at_ravel$ time dd if=/dev/zero of=foo bs=1024 count=1024
>     1024+0 records in
>     1024+0 records out
> 
>     real    0m0.042s
>     user    0m0.000s
>     sys     0m0.010s
> 
> 
> We should probably figure out where the time is lost. Force a
> write-disconnect and write the file. That should really take no time at
> all. Then reconnect (cfs wr) and do the operation while running vmstat
> 1 in a second terminal. That should show whether we're hogging the CPU,
> or trashing the disk, or simply using too much memory and forcing the
> machine to swap too much.
> 
> Oh, and dual CPU should theoretically be better, because the application
> and venus are not fighting each other over the same CPU. If it weren't
> the fact that your worst cases are client & server on the same machine,
> I would have suspected network related problems. The only thing I can
> think of right now, is that RVM modifications use fsync to force changes
> to disk, and I've noticed before that fsync on Linux is extremely slow
> when there are a lot of dirty buffers waiting for writeout, and that
> heavy writeout activity stalls read/page-in operation significantly.
> 
> Jan
> 
> 
Received on 2003-01-31 04:45:34