In message <[EMAIL PROTECTED]>, Matthew Dillon writes:
> VN calls vm_pager_strategy() which collects I/O in filesystem buffers
> (bp)'s in order to cluster the I/O, and you cannot initiate I/O on
> filesystem buffers without a valid b_dev.
>
> So, the jist of the problem is that in order to get reasonable performance
> out of the thing (i.e. not issue 4K I/O's to the disk), we have to use
> filesystem buffers which means the bp must be properly initialized.
vm_pager_strategy() branches out based on the object type and ends up
in swap_pager_strategy() which only uses b_dev after calling swstrategy()
then only in a diagnostic printf which we had better never reach.
swstrategy() which initializes bp->b_dev to the right physical device.
I'm afraid I don't see why or where we would need the bogus /dev/drum dev_t.
Furthermore, since we have already clustered above the VN device,
I seriously doubt the utility of doing it again between VN and the
swapdevice.
--
Poul-Henning Kamp FreeBSD coreteam member
[EMAIL PROTECTED] "Real hackers run -current on their laptop."
FreeBSD -- It will take a long time before progress goes too far!
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