Re: DMA transfers in 2.5.67

[Chuck Ebbert <76306.1226@compuserve.com>]

Andrew Morton wrote:


> > Chuck Ebbert <76306.1226@compuserve.com> wrote:
> > >
> > > # mount /ext3_fs
> > > # time dd if=/ext3_fs/100MiB_file of=/dev/null bs=32k
> > > 
> > >   2.4.20aa1 : 3.3 sec (exactly what I expect to see)
> > >   2.5.66    : 6.6 sec
> > 
> > With this test 2.4 will leave a lot more unwritten dirty data in memory.
> > 
> > You should include a `sync' in the timings.
> 
> Well you should include the sync if you're writing to disk ;)


  :)

  All is not beer and skittles here with Andrea's kernel, though.
Sometimes instead of 31MB/sec I get this with 1 sequential stream:


 1  0  0      0   1232   1120  47988   0   0 14928     0 3834  7534   1  44  55
 1  0  0      0   1372   1120  47848   0   0 14704     0 3778  7446   0  32  68
 1  0  0      0   1464   1064  47816   0   0 14880     0 3822  7501   1  43  56
 1  0  0      0   1336   1064  47944   0   0 14844     0 3813  7493   0  29  71
 1  0  0      0   1432   1064  47848   0   0 14748    32 3800  7467   0  41  59
 1  0  0      0   1532   1064  47748   0   0 13976     0 3596  7045   1  33  66
 


  Pretty high context switch and interrupt rates for a PPro 200, huh?

  And I can't reliably reproduce it (so far...)

------
 Chuck