svn commit: r312694 - in head: sys/cam/ctl usr.sbin/ctladm
Konstantin Belousov
kostikbel at gmail.com
Tue Jan 24 13:14:34 UTC 2017
On Tue, Jan 24, 2017 at 12:13:41PM +0000, Alexander Motin wrote:
> Author: mav
> Date: Tue Jan 24 12:13:41 2017
> New Revision: 312694
> URL: https://svnweb.freebsd.org/changeset/base/312694
>
> Log:
> Make CTL ramdisk backend a real RAM disk.
>
> If "capacity" LU option is set, ramdisk backend now implements featured
> thin provisioned disk, storing data in malloc(9) allocated memory blocks
> of pblocksize bytes (default PAGE_SIZE or 4KB). Additionally ~0.2% of LU
> size is used for indirection tree (bigger pblocksize reduce the overhead).
> Backend supports all unmap and anchor operations. If configured capacity
> is overflowed, proper error conditions are reported.
>
> If "capacity" LU option is not set, the backend operates mostly the same
> as before without allocating real storage: writes go to nowhere, reads
> return zeroes, reporting that all LBAs are unmapped.
>
> This backend is still mostly oriented on testing and benchmarking (it is
> still a volatile RAM disk), but now it should allow to run real FS tests,
> not only simple dumb dd.
This sounds too much like malloc-backed md(4).
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