Date: Wed, 24 Oct 2007 21:44:52 +0200 From: Kris Kennaway <kris@FreeBSD.org> To: John Baldwin <jhb@freebsd.org> Cc: stable@freebsd.org, Alfred Perlstein <alfred@freebsd.org>, Robert Watson <rwatson@freebsd.org> Subject: Re: LOCK_PROFILING in -stable Message-ID: <471FA0B4.1000904@FreeBSD.org> In-Reply-To: <200710241310.22969.jhb@freebsd.org> References: <20071019232846.GQ31826@elvis.mu.org> <20071020192717.GX31826@elvis.mu.org> <471B143E.7050200@FreeBSD.org> <200710241310.22969.jhb@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
John Baldwin wrote: > On Sunday 21 October 2007 04:56:30 am Kris Kennaway wrote: >> Alfred Perlstein wrote: >>> * Robert Watson <rwatson@FreeBSD.org> [071020 10:21] wrote: >>>> On Sat, 20 Oct 2007, Kris Kennaway wrote: >>>> >>>>> Alfred Perlstein wrote: >>>>>> Hey guys, I have LOCK_PROFILING done for a product based on FreeBSD-6, >>>>>> this means I can relatively easily backport LOCK_PROFILING from > FreeBSD-7 >>>>>> to FreeBSD-6. >>>>>> >>>>>> Do we want this? >>>>>> >>>>>> I'd like to do it if people want it. >>>>> I think it should be done, performance is a lot better than the old 6.x >>>>> version and it also adds another very useful performance metric (time >>>>> spent waiting for the lock). The only concern is that it doesn't break >>>>> ABI support when not compiled in, but I'm pretty sure you've already > told >>>>> me this is OK. Thanks for looking at this. >>>> This is my feeling also -- I would consider ABI breakage a show stopper > for >>>> 6.x, but feel otherwise that the new code is much more mature and capable >>>> and would be quite beneficial to people building appliances and related >>>> products on 6.x. You might check with Attilio about whether there are any >>>> remaining outstanding issues that need to be resolved first, and make > sure >>>> to send a heads up out on stable@ and put a note in UPDATING that the >>>> option and details have changed. >>> I still get confused as to the meaning of this... >>> >>> It only breaks ABI when it's enabled. >>> >>> I think that is OK, right? >>> >> Yes, that is fine. Other existing debugging options also break ABI when >> enabled, so it's OK. > > Well, MUTEX_PROFILING does and LOCK_PROFILING is the same thing. This option > is a known "special case" that breaks the ABI and people using it should > already be aware of that. Other debugging options (INVARIANTS, WITNESS, > etc.) do not affect the ABI. > DEBUG_VFS_LOCKS and/or DEBUG_LOCKS also break the ABI. Kris
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?471FA0B4.1000904>