svn commit: r340676 - in head/sys: kern sys
Mateusz Guzik
mjg at FreeBSD.org
Tue Nov 20 14:58:42 UTC 2018
Author: mjg
Date: Tue Nov 20 14:58:41 2018
New Revision: 340676
URL: https://svnweb.freebsd.org/changeset/base/340676
Log:
Implement unr64
Important users of unr like tmpfs or pipes can get away with just
ever-increasing counters, making the overhead of managing the state
for 32 bit counters a pessimization.
Change it to an atomic variable. This can be further sped up by making
the counts variable "allocate" ranges and store them per-cpu.
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D18054
Modified:
head/sys/kern/subr_unit.c
head/sys/sys/systm.h
Modified: head/sys/kern/subr_unit.c
==============================================================================
--- head/sys/kern/subr_unit.c Tue Nov 20 14:52:43 2018 (r340675)
+++ head/sys/kern/subr_unit.c Tue Nov 20 14:58:41 2018 (r340676)
@@ -98,6 +98,19 @@ static struct mtx unitmtx;
MTX_SYSINIT(unit, &unitmtx, "unit# allocation", MTX_DEF);
+#ifdef UNR64_LOCKED
+uint64_t
+alloc_unr64(struct unrhdr64 *unr64)
+{
+ uint64_t item;
+
+ mtx_lock(&unitmtx);
+ item = unr64->counter++;
+ mtx_unlock(&unitmtx);
+ return (item);
+}
+#endif
+
#else /* ...USERLAND */
#include <bitstring.h>
Modified: head/sys/sys/systm.h
==============================================================================
--- head/sys/sys/systm.h Tue Nov 20 14:52:43 2018 (r340675)
+++ head/sys/sys/systm.h Tue Nov 20 14:58:41 2018 (r340676)
@@ -523,6 +523,32 @@ int alloc_unr_specific(struct unrhdr *uh, u_int item);
int alloc_unrl(struct unrhdr *uh);
void free_unr(struct unrhdr *uh, u_int item);
+#if defined(__mips__) || defined(__powerpc__)
+#define UNR64_LOCKED
+#endif
+
+struct unrhdr64 {
+ uint64_t counter;
+};
+
+static __inline void
+new_unrhdr64(struct unrhdr64 *unr64, uint64_t low)
+{
+
+ unr64->counter = low;
+}
+
+#ifdef UNR64_LOCKED
+uint64_t alloc_unr64(struct unrhdr64 *);
+#else
+static __inline uint64_t
+alloc_unr64(struct unrhdr64 *unr64)
+{
+
+ return (atomic_fetchadd_64(&unr64->counter, 1));
+}
+#endif
+
void intr_prof_stack_use(struct thread *td, struct trapframe *frame);
void counted_warning(unsigned *counter, const char *msg);
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