Write throughput in >= 2.4.10

Write throughput in >= 2.4.10

[Zlatko Calusic]

It looks like recent kernels have some serious trouble during simple
writing of files. Throughput is cut to half.

2.4.12-ac3 (Riel VM):

   procs                      memory    swap          io     system         cpu
 r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us  sy  id
 0  4  1      0   2548   7652 369104   0   0     0 21992  291   592   0  23  77
 0  4  1      0   2556   7652 369104   0   0     0 22500  280   175   0   3  97
 0  4  1      0   3064   7652 368588   0   0     8 19644  278   202   0   4  96
...

2.4.13-pre4 (Andrea/Linus VM):

   procs                      memory    swap          io     system         cpu
 r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us  sy  id
 1  1  1  30312   2884   2304 384076   0  28     0  7784  199   241   0  12  88
 0  1  1  30316   2068   2256 385772   0 132     4  7900  186   188   1   8  91
 0  1  0  30316   3960   2232 384140   0   0     8  6744  179   204   0   4  96
...

'bo' column is the one to check out... I copied just 3 lines, but they
are all alike. 2.4.13-pre ends up with 11MB/sec, where -ac kernels are
over 20MB/sec (during sequential writing of big files - ext2 of course).

Also it looks like pre4 swaps when it is not necessary to do so. With
380MB in page cache I don't expect any swap traffic at all.
-- 
Zlatko

Re: Write throughput in >= 2.4.10

[Marcelo Tosatti]

On 18 Oct 2001, Zlatko Calusic wrote:

> It looks like recent kernels have some serious trouble during simple
> writing of files. Throughput is cut to half.
> 
> 2.4.12-ac3 (Riel VM):
> 
>    procs                      memory    swap          io     system         cpu
>  r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us  sy  id
>  0  4  1      0   2548   7652 369104   0   0     0 21992  291   592   0  23  77
>  0  4  1      0   2556   7652 369104   0   0     0 22500  280   175   0   3  97
>  0  4  1      0   3064   7652 368588   0   0     8 19644  278   202   0   4  96
> ...
> 
> 2.4.13-pre4 (Andrea/Linus VM):
> 
>    procs                      memory    swap          io     system         cpu
>  r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us  sy  id
>  1  1  1  30312   2884   2304 384076   0  28     0  7784  199   241   0  12  88
>  0  1  1  30316   2068   2256 385772   0 132     4  7900  186   188   1   8  91
>  0  1  0  30316   3960   2232 384140   0   0     8  6744  179   204   0   4  96
> ...
> 
> 'bo' column is the one to check out... I copied just 3 lines, but they
> are all alike. 2.4.13-pre ends up with 11MB/sec, where -ac kernels are
> over 20MB/sec (during sequential writing of big files - ext2 of course).
> 
> Also it looks like pre4 swaps when it is not necessary to do so. With
> 380MB in page cache I don't expect any swap traffic at all.

Zlatko, 

Could you please try 2.4.12-pre3 instead pre4 ?

Linus has made some changes and I want to see if those are partly
responsible for the problems you're seeing.

Thanks

Re: Write throughput in >= 2.4.10

[Zlatko Calusic]

Marcelo Tosatti <marcelo@conectiva.com.br> writes:

> On 18 Oct 2001, Zlatko Calusic wrote:
> 
> > It looks like recent kernels have some serious trouble during simple
> > writing of files. Throughput is cut to half.
> > 
[snip]

> 
> Zlatko, 
> 
> Could you please try 2.4.12-pre3 instead pre4 ?
> 
> Linus has made some changes and I want to see if those are partly
> responsible for the problems you're seeing.
> 

pre3 behaves exactly the same, so pre4 is not the culprit.
-- 
Zlatko