Re: question on readahead and sync mounting

[Jeff Moyer]

Oliver Neukum <oliver@xxxxxxxxxx> writes:

> Am Dienstag, 23. Februar 2010 00:48:39 schrieben Sie:
>> Please, Refer to below articles to understand readahead essentially.
>> 
>> http://lwn.net/Articles/235164/ (On-demand readahead by corbet)
>> http://kernelnewbies.org/Linux_2_6_23#head-102af265937262a7a21766ae58fddc1a29a5d8d7(
>> On-demand read-ahead on Linux 2.6.23)
>
> OK, I am looking for a way to make sure read requests on a SCSI drive
> actually hit the bus after a certain event. Is there a way to do this without
> tossing away the whole cache?

I'm not sure I understand what you're asking, but it sounds like you
want to do an O_DIRECT read.  Open the file with O_DIRECT, then pass
a properly-aligned buffer to the read(2) call.

Cheers,
Jeff
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