Date: Fri, 30 Nov 2018 08:46:18 -0800 (PST) From: "Rodney W. Grimes" <freebsd@pdx.rh.CN85.dnsmgr.net> To: Warner Losh <imp@bsdimp.com> Cc: Alexey Dokuchaev <danfe@freebsd.org>, Eugene Grosbein <eugen@grosbein.net>, src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, Steven Hartland <steven.hartland@multiplay.co.uk>, svn-src-head@freebsd.org, Cy Schubert <Cy.Schubert@cschubert.com> Subject: Re: svn: head/usr.bin: . trim Message-ID: <201811301646.wAUGkICh019024@pdx.rh.CN85.dnsmgr.net> In-Reply-To: <CANCZdfpEgOrPDbwe%2BnKAYdi6wo-=odpcuUnj4fjYrsUeTC5Xpw@mail.gmail.com>
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> On Fri, Nov 30, 2018 at 5:57 AM Alexey Dokuchaev <danfe@freebsd.org> wrote: > > > On Fri, Nov 30, 2018 at 07:27:46PM +0700, Eugene Grosbein wrote: > > > 30.11.2018 18:55, Alexey Dokuchaev wrote: > > > > > > >>> Another point: the manpage says, "It is only relevant for flash based > > > >>> storage devices that use wear-leveling algorithms", which is an > > argument > > > >>> against generic "trim". I would mind less of it would be called > > ftrim(8) > > > >>> or ssd_trim(8) or flash_trim(8), but still prefer Maxim's approach. > > > > > > [skip] > > > > > > > Yes, I understand you. Like I've said, a little more > > flash-media-related > > > > name would perhaps be more appropriate for such an utility. > > > > > > This excludes virtio_blk and ZFS. Perhaps, manpage should be corrected > > > as quoted phrase has been taken from news -E description as is. > > > > How about mtrim(8) or media_trim(8)? I vaguely when back in times misc/mc > > was installed as bin/midc because some commercial Unix implementation had > > "mc" as a "media copy" command or something like that. > > > > We should just put it in dd and remove this experiment. Both of these > suggested names are horrible. They are too specific. And the notion that > trim is too generic may have some merit, but the cure is worse than the > disease. > > So I'm back to my point: we should just put it into dd and move on with our > lives. It's really the right place for it. > > Why? > > Because then we can have 'dd if=image of=/dev/foo conf=sparse,erase' and it conf -> conv, and why erase? We are not actually erasing anything during this "copy" operation. I am having some confusion as to how the above would actually do the same thing that trim(8) implements. I do not really care if this is implemented as trim(8) or part of dd, either way is reasonable, though I am upset at repeating the discussion that already occured pre commit. Seems not enough committers follow hackers any more, so that has become a poor forum for vettting ideas, and now we post commit vet them on -commit. > will erase the bits of the drive that are all 0's. We won't have to resort > to weird hacks to make most of them trimmed. While this works only on media > where trim is persistently 0's, that describes all modern flash media and > most (all?) of the virtualization / thin storage scenarios I'm aware of. > You can't do that with the current utility, at least not w/o a lot of > effort. If your reading from file image and writting to dev foo I do not see that description matching the above command invocation. I think it would be: dd if=/dev/foo of=/dev/foo conv=noerror,sync,trim sparse is not involved, it is for files, not devices. erase imho is the wrong keyword, nothing in the trim/delete world calls this operation erase do they? trim could imply noerror,sync. -- Rod Grimes rgrimes@freebsd.org
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