Date: Tue, 26 Nov 2019 06:55:22 -0600 From: Mike Karels <mike@karels.net> To: "Rodney W. Grimes" <freebsd-rwg@gndrsh.dnsmgr.net> Cc: Warner Losh <imp@bsdimp.com>, "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: Re: Killing Giant for 13 Message-ID: <201911261255.xAQCtMfb061390@mail.karels.net> In-Reply-To: Your message of Tue, 26 Nov 2019 01:17:38 -0800. <201911260917.xAQ9Hcf1001914@gndrsh.dnsmgr.net>
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Responding both to Warner's original message and to Rod: > > I'd like to kill Giant in 13 and schedule a firm removal date. > > = > > The issues are (a) old drivers that aren't MP safe (b) some console / = ATKBD > > interactions (c) newbus and (d) a few stays that haven't been characte= rized. > > = > > (a) should be deleted or updated before the deadline > > (b) should be fixed by $SOMEONE[tm] > > (c) there's some work underway to refine the locking protocols to allo= w one > > to not have Giant held (there's real questions about how effective it = is > > when things sleep or contend) > > (d) I'm researching. > > = > > Would there be support for setting a firm deadline for Giant removal o= f > > around June 2020? This would be months ahead of a speculative 13.0 tim= eline > > (Earliest would be December 2020, latest would be maybe October 2021,= the > > exact details aren't super relevant for a June target date). > > = > > This is a preliminary inquiry to get a feel for support for this optio= n and > > to gather additional issues and requirements. Comments? I think we really need to get rid of Giant. It was a useful transition measure, but the transition to SMP should be long since over. +1 on Warner's proposal. > I see one reply to this, yet am seeing commits killing drivers, that > at least on surface appear to be not so old, and possibly relevant. > Though I have no objectionion to the removal of GIANT, I do have objecti= on > to what appears to be execuction before research and discussion, especia= lly > as I believe the item would of be under (d) above, as I do not consider > a driver that came into the tree at 10.0 "OLD". Although Warner used the word "old", that would not be the reason for dropping drivers that use Giant. The reason is that they are not MP safe. If no one will upgrade them, it doesn't matter when they were introduced. I think the project needs to work to reduce technical debt, and I applaud Warner for tackling this. Mike
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