mfi timeouts

[John Baldwin]

On Wednesday, February 27, 2013 12:58:11 am rihad wrote:
> Now about this part taken from here 
> http://lists.freebsd.org/pipermail/freebsd-scsi/2011-March/004839.html
>  > By issuing a dummy read operation (thus forcing a flush of data 
> buffers), this issue is largely averted.
> 
> Does this mean that battery-backed cache (BBU) is effectively rendered 
> useless, as all write operations are forced on to the disk platters on 
> every interrupt?

No, this is a very different level.  This is forcing pending PCI DMA 
transactions on the PCI bus to flush by doing a read, not forcing I/O
buffers to be flushed to disk.

-- 
John Baldwin