Date: Fri, 11 May 2018 14:47:35 -0400 From: Mark Johnston <markj@FreeBSD.org> To: Matt Macy <mmacy@FreeBSD.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r333466 - in head: contrib/bmake sys/conf sys/kern sys/modules/epoch_test sys/sys sys/tests/epoch Message-ID: <20180511184735.GA34339@raichu> In-Reply-To: <201805101755.w4AHtPRt028900@repo.freebsd.org> References: <201805101755.w4AHtPRt028900@repo.freebsd.org>
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On Thu, May 10, 2018 at 05:55:25PM +0000, Matt Macy wrote: > Author: mmacy > Date: Thu May 10 17:55:24 2018 > New Revision: 333466 > URL: https://svnweb.freebsd.org/changeset/base/333466 > > Log: > Add simple preempt safe epoch API > > Read locking is over used in the kernel to guarantee liveness. This API makes > it easy to provide livenes guarantees without atomics. > > Includes epoch_test kernel module to stress test the API. > > Documentation will follow initial use case. > > Test case and improvements to preemption handling in response to discussion > with mjg@ > > Reviewed by: imp@, shurd@ > Approved by: sbruno@ > > Added: > head/sys/kern/subr_epoch.c (contents, props changed) > head/sys/modules/epoch_test/ > head/sys/modules/epoch_test/Makefile (contents, props changed) > head/sys/sys/epoch.h (contents, props changed) > head/sys/tests/epoch/ > head/sys/tests/epoch/epoch_test.c (contents, props changed) > Modified: > head/contrib/bmake/job.c > head/sys/conf/files > head/sys/conf/kern.pre.mk > head/sys/kern/kern_malloc.c > head/sys/kern/kern_synch.c > head/sys/kern/subr_trap.c > head/sys/kern/subr_turnstile.c > head/sys/sys/proc.h > head/sys/sys/turnstile.h > > Modified: head/sys/sys/proc.h > ============================================================================== > --- head/sys/sys/proc.h Thu May 10 17:22:04 2018 (r333465) > +++ head/sys/sys/proc.h Thu May 10 17:55:24 2018 (r333466) > @@ -243,6 +243,7 @@ struct thread { > > /* Cleared during fork1() */ > #define td_startzero td_flags > + u_char td_epochnest; /* (k) Private thread epoch nest counter */ It looks like td_epochnest was inteded to be in the zeroed section, but td_startzero still points to td_flags. > int td_flags; /* (t) TDF_* flags. */ > int td_inhibitors; /* (t) Why can not run. */ > int td_pflags; /* (k) Private thread (TDP_*) flags. */ > @@ -355,6 +356,7 @@ struct thread { > int td_lastcpu; /* (t) Last cpu we were on. */ > int td_oncpu; /* (t) Which cpu we are on. */ > void *td_lkpi_task; /* LinuxKPI task struct pointer */ > + TAILQ_ENTRY(thread) td_epochq; /* (t) Epoch queue. */ > };
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