Date: Wed, 29 Aug 2018 11:18:57 -0400 From: Mark Johnston <markj@freebsd.org> To: Alexander Leidinger <Alexander@leidinger.net> Cc: freebsd-current@freebsd.org Subject: Re: old top and new -current: missing arcstat sysctl Message-ID: <20180829151857.GA2709@raichu> In-Reply-To: <20180829074431.Horde.NYx7i7jvhNMNuTj-hSYfzSk@webmail.leidinger.net> References: <20180828084015.Horde.JUeG828X_SDlJjeJdfmH7pV@webmail.leidinger.net> <d7834f4e-f1ca-c02a-6fe1-472b8737058c@freebsd.org> <20180828144842.GA29917@raichu> <20180829074431.Horde.NYx7i7jvhNMNuTj-hSYfzSk@webmail.leidinger.net>
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On Wed, Aug 29, 2018 at 07:44:31AM +0200, Alexander Leidinger wrote: > > Quoting Mark Johnston <markj@freebsd.org> (from Tue, 28 Aug 2018 > 10:48:42 -0400): > > > On Tue, Aug 28, 2018 at 10:25:39AM -0400, Allan Jude wrote: > >> On 2018-08-28 02:40, Alexander Leidinger wrote: > >> > Hi, > >> > > >> > top reports missing sysctl kstat.zfs.misc.arcstats.other_size for > >> > 12.0-alpha3 with a top from an old-ish -current. > >> > > >> > Is/will this be handled via a compat-11 sysctl (my kernel is without > >> > compat-xx), or did this slip through? > > >> That is not something that a compat-xx package can handle. > > > > s/package/kernel option/? > > Sorry, the COMPAT_FREEBSDx kernel options was what I had in mind when > I wrote this. > > >> That arcstat was broken up into 3 individual stats, which the > >> 12.0-alpha3 version of top will sum together for you. > >> > >> I don't think we've had compat shims like this for previous versions of > >> top, I recall having similar issues when the 'laundry' counter was > >> introduced. > > > > IIRC that would have been the inverted case of running a newer top(1) > > with an older kernel lacking the v_laundry_pages sysctl. In general I'd > > expect us to support running an older top(1) with newer kernels if we > > don't have to bend over backwards to provide compatibility. > > If the new top is summing the 3 up anyway, it sounds like we could > provide the old one as backwards compatibility, even if it is > redundant. I rather have an redundant counter and an old top working > (in the generic case of what we promise to our users; in this specific > case for me I just need to get around to update the jails on the > corresponding systems), than bailing out without displaying anything. I'm inclined to agree, especially since this (running older top(1)s) has come up before when I removed some VM sysctls: https://reviews.freebsd.org/D16943
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