Re: Linux 2.6.29

David Rees
2009-04-03T22:57:29Z

On Fri, Apr 3, 2009 at 3:32 PM, Janne Grunau <j@jannau.net> wrote:
> On Fri, Apr 03, 2009 at 05:57:05PM -0400, Jeff Garzik wrote:
>> Just curious, does MythTV need fsync(), or merely to tell the kernel to
>> begin asynchronously writing data to storage?
>
> quoting the TheadedFileWriter comments
>
> /*
>  *   NOTE: This doesn't even try flush our queue of data.
>  *   This only ensures that data which has already been sent
>  *   to the kernel for this file is written to disk. This
>  *   means that if this backend is writing the data over a
>  *   network filesystem like NFS, then the data will be visible
>  *   to the NFS server after this is called. It is also useful
>  *   in preventing the kernel from buffering up so many writes
>  *   that they steal the CPU for a long time when the write
>  *   to disk actually occurs.
>  */

There is no need to fsync data on a NFS mount in Linux anymore. All
NFS mounts are mounted sync by default now unless you explicitly
specify otherwise (and then you should then know what you're getting
in to).

-Dave