Re: [Xen-devel] Benchmark Xen writes with sync - Xen ignores fsync, O_SYNC?

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 11 Apr 2012, Pablo Llopis wrote:
> Yes, I am using "xm create" to instance the guest (xen-tools to actually 
> create the guest image). And yes, I am pretty
> sure I am using blkback in combination with a loopback device (I'm using 
> file:/ after all). But I thought the xend
> backend systems would somehow, at least, force a fsync() for that file. It 
> seems that when using file:/ sync operations
> don't really ensure that contents are being synced to disk, but only to the 
> loopback-mounted file, which is probably still
> affected by the pagecache (but that's only a guess).Â
> 
> For the record, I tried with phy:/ and a LVM volume and everything works as 
> expected (i.e. sync and fsync operations sync
> data to disk).Â

That would be the best solution with Xen 4.1 and it is also the fastest.

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