Messages in this thread | | | Date | Sun, 12 Mar 2006 17:15:06 -0500 | From | Mark Lord <> | Subject | Re: Readahead value 128K? (was Re: Drastic Slowdown of 'fseek()' Calls From 2.4 to 2.6 -- VMM Change?) |
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Marr wrote: > > I tried turning 'readahead' off entirely ('hdparm -A0 /dev/hda') and, although
No, that should be "hdparm -a0 /dev/hda" (lowercase "-a"). And the same "-a" for all of your other test variants.
If you did it all with "-A", then the results are invalid, and need to be redone.
The hdparm manpage explains this, but in a nutshell, "-A" is the low-level drive firmware "look-ahead" mechanism, whereas "-a" is the Linux kernel "read-ahead" scheme.
In general, most uppercase hdparm flags are drive *firmware* settings.
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