Re: Blocked processes <=> Elevator starvation?

[Giuliano Pochini <pochini@denise.shiny.it>]

> I just reproduced the problem in test10-pre7.  Here's the
> output you requested:
> 
> 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  2  2      0  45764  76000  59520   0   0     0   509  272   508   0   0 100
>   0  2  2      0  45300  76324  59520   0   0     0   636  276   548   1   0  99
>   0  2  2      0  44896  76680  59520   0   0     0   636  273   523   0   0 100
>   0  2  2      0  44088  77392  59520   0   0     0   650  281  1307   0   7  93
>   1  1  2      0  43736  77680  59548   0   0     0  1279  908  2637   1   8  91
>   0  2  3      0  43072  78040  59592   0   0     0  1660 1281  4119   5   6  89
> 
>  >>> /var/log/kernel output stopped being emitted here <<<
>  >>>  CRUNCH!  <<<
> 
>   0  2  3      0  42656  78384  59592   0   0     0   259  271   551   0   0 100
>   0  2  3      0  42656  78384  59592   0   0     0     5  271   499   0   0 100
>   0  2  3      0  42656  78384  59592   0   0     0     5  272   511   0   2  98
>   0  2  3      0  42656  78384  59592   0   0     0     4  268   502   0   0 100
>   0  2  3      0  42656  78384  59592   0   0     0     5  272   508   0   0 100
>   0  2  3      0  42656  78384  59592   0   0     0     5  274   523   0   0 100


test7 had the problem that when the rq queue if full new requests are no
longer
merged together (the disk is slow because it writes a lot of 512 bytes blocks
instead of 128K blocks).  There is a patch for this. There still is the
problem that when the rq queue if full other processes can no more access to
*any*
device that uses ll_rw_block() and they remain blocked in D state.


Bye.


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