Re: O_DIRECT question

[Andrea Arcangeli]

On Tue, Jan 30, 2007 at 08:57:20PM +0100, Andrea Arcangeli wrote:
> Please try yourself, it's simple enough:
> 
>        time dd if=/dev/hda of=/dev/null bs=16M count=100
>        time dd if=/dev/hda of=/dev/null bs=16M count=100 iflag=sync

sorry, reading won't help much to exercise sync ;). But the direct
line is enough to show the effect of I/O pipeline stall. To
effectively test sync of course you want to write to a file instead
(unless you want to wipe out /dev/hda ;)
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