Re: Readahead value 128K? (was Re: Drastic Slowdown of 'fseek()'Calls From 2.4 to 2.6 -- VMM Change?)

[Linda Walsh]

Marr wrote:
> On Sunday 05 March 2006 6:02pm, Linda Walsh wrote:
> > Does this happen with a seek call as well, or is this limited
> > to fseek?
> >
> > if you look at "hdparm's" idea of read-ahead, what does it say
> > for the device?.  I.e.:
> >
> > hdparm /dev/hda:
> >
> > There is a line entitled "readahead".  What does it say?
>
> Linda,
>
> I don't know (based on your email addressing) if you were directing this 
> question at me, but since I'm the guy who originally reported this issue, 
> here are my 'hdparm' results on my (standard Slackware 10.2) ReiserFS 
> filesystem:
>
>    2.6.13 (with 'nolargeio=1' for reiserfs mount): 
>       readahead    = 256 (on)
>
>    2.6.13 (without 'nolargeio=1' for reiserfs mount): 
>       readahead    = 256 (on)
>
>    2.4.31 ('nolargeio' option irrelevant/unavailable for 2.4.x): 
>       readahead    = 8 (on)
>
> *** Please CC: me on replies -- I'm not subscribed.
>
> Regards,
> Bill Marr
--------
   Could you retry your test with read-ahead set to a smaller
value?  Say the same as in 2.4 (8) or 16 and see if that changes
anything?

hdparm -a8 /dev/hdx
 or
hdparm -a16 /dev/hdx



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