[sheepdog] [PATCH 3/6] sheep, sockfd cache: cache more than one FD for each node

[Christoph Hellwig]

On Mon, Jun 25, 2012 at 01:56:42PM +0800, Liu Yuan wrote:
> Dunno others, but current Linux virtio_blk driver can only issue as much
> as 4 requests in one go. IDE driver is less than 4 I think. From the
> driver perspective, it seems that only scsi driver can issue more than 4
> requests in one go, but QEMU support to emulate scsi disk ?
> 
> Anyway, this is just a hint. Suppose request size from guest is 512k,
> then 4M / 512k = 8, so at most 8 request can be issued to one sheep
> object. So I think 8 is enough.

Please add the above as a comment for the constant.  It might also make
sense to allow tuning this value.