Re: [dm-devel] dd to a striped device with 9 disks gets much lower throughput when oflag=direct used

[Christoph Hellwig <hch infradead org>]

On Thu, Jan 26, 2012 at 05:06:42PM -0800, Richard Sharpe wrote:
> Why do I see such a big performance difference? Does writing to the
> device also use the page cache if I don't specify DIRECT IO?

Yes.  Trying adding conv=fdatasync to both versions to get more
realistic results.