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Date:      Wed, 14 Nov 2018 00:12:05 +0000 (UTC)
From:      Matt Macy <mmacy@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r340420 - head/sys/kern
Message-ID:  <201811140012.wAE0C5Y1003356@repo.freebsd.org>
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Author: mmacy
Date: Wed Nov 14 00:12:04 2018
New Revision: 340420
URL: https://svnweb.freebsd.org/changeset/base/340420

Log:
  epoch(9) revert r340097 - no longer a need for multiple sections per cpu
  
  I spoke with Samy Bahra and recent changes to CK to make ck_epoch_call and
  ck_epoch_poll not modify the record have eliminated the need for this.

Modified:
  head/sys/kern/subr_epoch.c

Modified: head/sys/kern/subr_epoch.c
==============================================================================
--- head/sys/kern/subr_epoch.c	Tue Nov 13 23:57:34 2018	(r340419)
+++ head/sys/kern/subr_epoch.c	Wed Nov 14 00:12:04 2018	(r340420)
@@ -63,8 +63,7 @@ static MALLOC_DEFINE(M_EPOCH, "epoch", "epoch based re
 
 TAILQ_HEAD (epoch_tdlist, epoch_tracker);
 typedef struct epoch_record {
-	ck_epoch_record_t er_read_record;
-	ck_epoch_record_t er_write_record;
+	ck_epoch_record_t er_record;
 	volatile struct epoch_tdlist er_tdlist;
 	volatile uint32_t er_gen;
 	uint32_t er_cpuid;
@@ -176,8 +175,7 @@ epoch_ctor(epoch_t epoch)
 	CPU_FOREACH(cpu) {
 		er = zpcpu_get_cpu(epoch->e_pcpu_record, cpu);
 		bzero(er, sizeof(*er));
-		ck_epoch_register(&epoch->e_epoch, &er->er_read_record, NULL);
-		ck_epoch_register(&epoch->e_epoch, &er->er_write_record, NULL);
+		ck_epoch_register(&epoch->e_epoch, &er->er_record, NULL);
 		TAILQ_INIT((struct threadlist *)(uintptr_t)&er->er_tdlist);
 		er->er_cpuid = cpu;
 	}
@@ -262,7 +260,7 @@ epoch_enter_preempt(epoch_t epoch, epoch_tracker_t et)
 	td->td_pre_epoch_prio = td->td_priority;
 	er = epoch_currecord(epoch);
 	TAILQ_INSERT_TAIL(&er->er_tdlist, et, et_link);
-	ck_epoch_begin(&er->er_read_record, &et->et_section);
+	ck_epoch_begin(&er->er_record, &et->et_section);
 	critical_exit();
 }
 
@@ -279,7 +277,7 @@ epoch_enter(epoch_t epoch)
 	td->td_epochnest++;
 	critical_enter();
 	er = epoch_currecord(epoch);
-	ck_epoch_begin(&er->er_read_record, NULL);
+	ck_epoch_begin(&er->er_record, NULL);
 }
 
 void
@@ -307,7 +305,7 @@ epoch_exit_preempt(epoch_t epoch, epoch_tracker_t et)
 #ifdef INVARIANTS
 	et->et_td = (void*)0xDEADBEEF;
 #endif
-	ck_epoch_end(&er->er_read_record, &et->et_section);
+	ck_epoch_end(&er->er_record, &et->et_section);
 	TAILQ_REMOVE(&er->er_tdlist, et, et_link);
 	er->er_gen++;
 	if (__predict_false(td->td_pre_epoch_prio != td->td_priority))
@@ -326,7 +324,7 @@ epoch_exit(epoch_t epoch)
 	MPASS(td->td_epochnest);
 	td->td_epochnest--;
 	er = epoch_currecord(epoch);
-	ck_epoch_end(&er->er_read_record, NULL);
+	ck_epoch_end(&er->er_record, NULL);
 	critical_exit();
 }
 
@@ -346,7 +344,7 @@ epoch_block_handler_preempt(struct ck_epoch *global __
 	int spincount, gen;
 	int locksheld __unused;
 
-	record = __containerof(cr, struct epoch_record, er_read_record);
+	record = __containerof(cr, struct epoch_record, er_record);
 	td = curthread;
 	locksheld = td->td_locks;
 	spincount = 0;
@@ -574,7 +572,7 @@ epoch_call(epoch_t epoch, epoch_context_t ctx, void (*
 	critical_enter();
 	*DPCPU_PTR(epoch_cb_count) += 1;
 	er = epoch_currecord(epoch);
-	ck_epoch_call(&er->er_write_record, cb, (ck_epoch_cb_t *)callback);
+	ck_epoch_call(&er->er_record, cb, (ck_epoch_cb_t *)callback);
 	critical_exit();
 	return;
 boottime:
@@ -598,7 +596,7 @@ epoch_call_task(void *arg __unused)
 		if (__predict_false((epoch = allepochs[i]) == NULL))
 			continue;
 		er = epoch_currecord(epoch);
-		record = &er->er_write_record;
+		record = &er->er_record;
 		if ((npending = record->n_pending) == 0)
 			continue;
 		ck_epoch_poll_deferred(record, &cb_stack);

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