Re: Asynchronous I/O Support

NikhilS wrote:
> Hi,
>
> "bgwriter doing aysncronous I/O for the dirty buffers that it is
> supposed to sync"
> Another decent use-case?
>
> Regards,
> Nikhils
> EnterpriseDB http://www.enterprisedb.com
>
> On 10/15/06, *Luke Lonergan* <llonergan(at)greenplum(dot)com
> <mailto:llonergan(at)greenplum(dot)com>> wrote:
>
> Martijn,
>
> On 10/15/06 10:56 AM, "Martijn van Oosterhout" <kleptog(at)svana(dot)org
> <mailto:kleptog(at)svana(dot)org>> wrote:
>
> > Have enough systems actually got to the point of actually supporting
> > async I/O that it's worth implementing?
>
> I think there are enough high end applications / systems that need it at
> this point.
>
> The killer use-case we've identified is for the scattered I/O
> associated
> with index + heap scans in Postgres. If we can issue ~5-15 I/Os in
> advance
> when the TIDs are widely separated it has the potential to increase
> the I/O
> speed by the number of disks in the tablespace being scanned. At this
> point, that pattern will only use one disk.
>

Is it worth considering using readv(2) instead?

Cheers

Mark