Date: Thu, 17 Mar 2011 14:36:16 -0400 From: Jung-uk Kim <jkim@FreeBSD.org> To: freebsd-hackers@FreeBSD.org Cc: Kostik Belousov <kostikbel@gmail.com>, Bruce Evans <brde@optusnet.com.au>, Maxim Dounin <mdounin@mdounin.ru> Subject: get_cyclecount(9) deprecation Message-ID: <201103171436.22283.jkim@FreeBSD.org>
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Both get_cyclecount(9) and cpu_ticks() do almost exactly the same
thing now assuming set_cputicker() is called with a correct function
before get_cyclecount() is used, which is true for x86, at least.
The only difference is get_cyclecount() may be inlined but I don't
see much gain from the current uses.
Please review the patch. Note I didn't really remove get_cyclecount()
just because some random third-party module may use it as it is a
documented feature while cpu_ticks is an internal KPI.
What do you think?
Jung-uk Kim
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Index: sys/kern/kern_ktr.c
===================================================================
--- sys/kern/kern_ktr.c (revision 219714)
+++ sys/kern/kern_ktr.c (working copy)
@@ -73,7 +73,7 @@ __FBSDID("$FreeBSD$");
#endif
#ifndef KTR_TIME
-#define KTR_TIME get_cyclecount()
+#define KTR_TIME cpu_ticks()
#endif
#ifndef KTR_CPU
Index: sys/kern/init_main.c
===================================================================
--- sys/kern/init_main.c (revision 219714)
+++ sys/kern/init_main.c (working copy)
@@ -560,7 +560,7 @@ SYSINIT(p0init, SI_SUB_INTRINSIC, SI_ORDER_FIRST,
static void
proc0_post(void *dummy __unused)
{
- struct timespec ts;
+ struct bintime bt;
struct proc *p;
struct rusage ru;
struct thread *td;
@@ -590,8 +590,8 @@ proc0_post(void *dummy __unused)
/*
* Give the ``random'' number generator a thump.
*/
- nanotime(&ts);
- srandom(ts.tv_sec ^ ts.tv_nsec);
+ bintime(&bt);
+ srandom(bt.sec ^ bt.frac);
}
SYSINIT(p0post, SI_SUB_INTRINSIC_POST, SI_ORDER_FIRST, proc0_post, NULL);
@@ -601,10 +601,10 @@ random_init(void *dummy __unused)
/*
* After CPU has been started we have some randomness on most
- * platforms via get_cyclecount(). For platforms that don't
- * we will reseed random(9) in proc0_post() as well.
+ * platforms via cpu_ticks(). For platforms that don't we will
+ * reseed random(9) in proc0_post() as well.
*/
- srandom(get_cyclecount());
+ srandom(cpu_ticks());
}
SYSINIT(random, SI_SUB_RANDOM, SI_ORDER_FIRST, random_init, NULL);
Index: sys/netinet/sctp_os_bsd.h
===================================================================
--- sys/netinet/sctp_os_bsd.h (revision 219714)
+++ sys/netinet/sctp_os_bsd.h (working copy)
@@ -129,7 +129,7 @@ MALLOC_DECLARE(SCTP_M_MCORE);
#if defined(SCTP_LOCAL_TRACE_BUF)
-#define SCTP_GET_CYCLECOUNT get_cyclecount()
+#define SCTP_GET_CYCLECOUNT cpu_ticks()
#define SCTP_CTR6 sctp_log_trace
#else
Index: sys/dev/de/if_devar.h
===================================================================
--- sys/dev/de/if_devar.h (revision 219714)
+++ sys/dev/de/if_devar.h (working copy)
@@ -903,7 +903,7 @@ typedef u_long tulip_cycle_t;
static __inline tulip_cycle_t
TULIP_PERFREAD(void)
{
- return (get_cyclecount());
+ return (cpu_ticks());
}
#define TULIP_PERFDIFF(s, f) ((f) - (s))
Index: sys/dev/random/randomdev_soft.c
===================================================================
--- sys/dev/random/randomdev_soft.c (revision 219714)
+++ sys/dev/random/randomdev_soft.c (working copy)
@@ -353,8 +353,8 @@ random_yarrow_write(void *buf, int count)
chunk = HARVESTSIZE;
if (i + chunk >= count)
chunk = (u_int)(count - i);
- random_harvest_internal(get_cyclecount(), (char *)buf + i,
- chunk, 0, 0, RANDOM_WRITE);
+ random_harvest_internal(cpu_ticks(), (char *)buf + i, chunk,
+ 0, 0, RANDOM_WRITE);
}
}
Index: sys/dev/random/harvest.c
===================================================================
--- sys/dev/random/harvest.c (revision 219714)
+++ sys/dev/random/harvest.c (working copy)
@@ -78,17 +78,16 @@ random_yarrow_deinit_harvester(void)
* Implemented as in indirect call to allow non-inclusion of
* the entropy device.
*
- * XXXRW: get_cyclecount() is cheap on most modern hardware, where cycle
- * counters are built in, but on older hardware it will do a real time clock
- * read which can be quite expensive.
+ * XXXRW: cpu_ticks() is cheap on most modern hardware, where cycle counters
+ * are built in, but on older hardware it will do a real time clock read
+ * which can be quite expensive.
*/
void
random_harvest(void *entropy, u_int count, u_int bits, u_int frac,
enum esource origin)
{
if (reap_func)
- (*reap_func)(get_cyclecount(), entropy, count, bits, frac,
- origin);
+ (*reap_func)(cpu_ticks(), entropy, count, bits, frac, origin);
}
/* Userland-visible version of read_random */
Index: sys/i386/include/cpu.h
===================================================================
--- sys/i386/include/cpu.h (revision 219714)
+++ sys/i386/include/cpu.h (working copy)
@@ -39,7 +39,6 @@
/*
* Definitions unique to i386 cpu support.
*/
-#include <machine/cputypes.h>
#include <machine/psl.h>
#include <machine/frame.h>
#include <machine/segments.h>
@@ -70,13 +69,8 @@ void swi_vm(void *);
static __inline uint64_t
get_cyclecount(void)
{
- struct bintime bt;
- if (cpu_class == CPUCLASS_486) {
- binuptime(&bt);
- return ((uint64_t)bt.sec << 56 | bt.frac >> 8);
- }
- return (rdtsc());
+ return (cpu_ticks());
}
#endif
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