Date: Wed, 23 May 2018 16:13:45 -0700 From: Matthew Macy <mmacy@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: 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: <CAPrugNo8_h5jnn2Yt250ZH1crwxHhK46QK1vfdyWssYjuuSAqQ@mail.gmail.com> In-Reply-To: <2281830.zrSQodBeDb@ralph.baldwin.cx> References: <201805231700.w4NH05hs047395@repo.freebsd.org> <2281830.zrSQodBeDb@ralph.baldwin.cx>
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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 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. -M
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