Date: Wed, 23 May 2018 20:40:37 -0400 From: "Jonathan T. Looney" <jtl@freebsd.org> To: Matthew Macy <mmacy@freebsd.org> Cc: John Baldwin <jhb@freebsd.org>, src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r334104 - in head/sys: netinet sys Message-ID: <CADrOrmtmSYtMt4vrqdFHrLqAArBaws8bAeynPa8X_sz7ui86uw@mail.gmail.com> In-Reply-To: <CAPrugNo8_h5jnn2Yt250ZH1crwxHhK46QK1vfdyWssYjuuSAqQ@mail.gmail.com> References: <201805231700.w4NH05hs047395@repo.freebsd.org> <2281830.zrSQodBeDb@ralph.baldwin.cx> <CAPrugNo8_h5jnn2Yt250ZH1crwxHhK46QK1vfdyWssYjuuSAqQ@mail.gmail.com>
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On Wed, May 23, 2018 at 7:13 PM, Matthew Macy <mmacy@freebsd.org> wrote: > > On Wed, May 23, 2018 at 11:52 AM, John Baldwin <jhb@freebsd.org> wrote: > > On Wednesday, May 23, 2018 05:00:05 PM Matt Macy wrote: > >> Author: mmacy > >> Date: Wed May 23 17:00:05 2018 > >> New Revision: 334104 > >> URL: https://svnweb.freebsd.org/changeset/base/334104 > >> > >> Log: > >> epoch: allow for conditionally asserting that the epoch context fields > >> are unused by zeroing on INVARIANTS builds > > > > Is M_ZERO really so bad that you need to make it conditional? > > In this case not at all. It's only exercised by sysctl handlers. I'm > mostly responding to an inquiry by jtl. However, gratuitous M_ZERO > usage does have a cumulative adverse performance impact. I appreciate you making this change. And, I do think it is worth avoiding M_ZERO where it is unnecessary, for the reason you state. > > I would probably have preferred something like 'M_ZERO_INVARIANTS' > > instead perhaps (or M_ZERO_EPOCH) that only controls M_ZERO and is > > still or'd with M_WAITOK or M_NOWAIT. > > Yes. I like that better too. Thanks. Yes, that does seem better. Thanks! Jonathan
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