Date: Tue, 24 Jan 2017 15:28:41 +0200 From: Alexander Motin <mav@FreeBSD.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r312694 - in head: sys/cam/ctl usr.sbin/ctladm Message-ID: <1e84f54f-89ab-e453-d80a-25d2a54ed378@FreeBSD.org> In-Reply-To: <20170124131427.GK2349@kib.kiev.ua> References: <201701241213.v0OCDfpa096425@repo.freebsd.org> <20170124131427.GK2349@kib.kiev.ua>
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On 24.01.2017 15:14, Konstantin Belousov wrote: > 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). Yes, it is. Just without memory copies and GEOM calls, and with some additional SCSI features. -- Alexander Motin
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