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Date: Fri, 28 May 2010 16:15:36 +0200
From: Piotr Hosowicz <piotr@...owicz.com>
To: Peter Zijlstra <peterz@...radead.org>
CC: Andrew Morton <akpm@...ux-foundation.org>,
Jens Axboe <jens.axboe@...cle.com>,
Divyesh Shah <dpshah@...gle.com>, Ingo Molnar <mingo@...e.hu>,
LKML <linux-kernel@...r.kernel.org>,
Piotr Hosowicz <piotr@...owicz.com>
Subject: Re: [PATCH] sched_clock: Provide local_clock() and improve documentation
On 28.05.2010 15:13, Peter Zijlstra wrote:
> On Thu, 2010-05-27 at 11:33 -0700, Andrew Morton wrote:
>
>> Cool, thanks. You didn't Cc a mailing list :(
>
> Oops, must have managed to wreck the CC list somewhere, restored LKML.
>
> How does the below look?
Earlier someone (you? I didn't write down) has published such a patch:
f4b87dee9
Index: linux-2.6/arch/parisc/kernel/ftrace.c
===================================================================
--- linux-2.6.orig/arch/parisc/kernel/ftrace.c
+++ linux-2.6/arch/parisc/kernel/ftrace.c
@@ -82,7 +82,7 @@ unsigned long ftrace_return_to_handler(u
unsigned long ret;
pop_return_trace(&trace, &ret);
- trace.rettime = cpu_clock(raw_smp_processor_id());
+ trace.rettime = local_clock();
ftrace_graph_return(&trace);
if (unlikely(!ret)) {
@@ -126,7 +126,7 @@ void prepare_ftrace_return(unsigned long
return;
}
- calltime = cpu_clock(raw_smp_processor_id());
+ calltime = local_clock();
if (push_return_trace(old, calltime,
self_addr, &trace.depth) == -EBUSY) {
Index: linux-2.6/include/linux/blkdev.h
===================================================================
--- linux-2.6.orig/include/linux/blkdev.h
+++ linux-2.6/include/linux/blkdev.h
@@ -1213,12 +1213,12 @@ int kblockd_schedule_work(struct request
#ifdef CONFIG_BLK_CGROUP
static inline void set_start_time_ns(struct request *req)
{
- req->start_time_ns = sched_clock();
+ req->start_time_ns = local_clock();
}
static inline void set_io_start_time_ns(struct request *req)
{
- req->io_start_time_ns = sched_clock();
+ req->io_start_time_ns = local_clock();
}
static inline uint64_t rq_start_time_ns(struct request *req)
Index: linux-2.6/include/linux/sched.h
===================================================================
--- linux-2.6.orig/include/linux/sched.h
+++ linux-2.6/include/linux/sched.h
@@ -1822,6 +1822,7 @@ extern void sched_clock_idle_wakeup_even
* clock constructed from sched_clock():
*/
extern unsigned long long cpu_clock(int cpu);
+extern unsigned long long local_clock(void);
extern unsigned long long
task_sched_runtime(struct task_struct *task);
Index: linux-2.6/kernel/lockdep.c
===================================================================
--- linux-2.6.orig/kernel/lockdep.c
+++ linux-2.6/kernel/lockdep.c
@@ -146,7 +146,7 @@ static DEFINE_PER_CPU(struct lock_class_
static inline u64 lockstat_clock(void)
{
- return cpu_clock(smp_processor_id());
+ return local_clock();
}
static int lock_point(unsigned long points[], unsigned long ip)
Index: linux-2.6/kernel/perf_event.c
===================================================================
--- linux-2.6.orig/kernel/perf_event.c
+++ linux-2.6/kernel/perf_event.c
@@ -214,7 +214,7 @@ static void perf_unpin_context(struct pe
static inline u64 perf_clock(void)
{
- return cpu_clock(raw_smp_processor_id());
+ return local_clock();
}
/*
Index: linux-2.6/kernel/rcutorture.c
===================================================================
--- linux-2.6.orig/kernel/rcutorture.c
+++ linux-2.6/kernel/rcutorture.c
@@ -239,8 +239,7 @@ static unsigned long
rcu_random(struct rcu_random_state *rrsp)
{
if (--rrsp->rrs_count < 0) {
- rrsp->rrs_state +=
- (unsigned long)cpu_clock(raw_smp_processor_id());
+ rrsp->rrs_state += (unsigned long)local_clock();
rrsp->rrs_count = RCU_RANDOM_REFRESH;
}
rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
Index: linux-2.6/kernel/sched.c
===================================================================
--- linux-2.6.orig/kernel/sched.c
+++ linux-2.6/kernel/sched.c
@@ -1670,7 +1670,7 @@ static void update_shares(struct sched_d
if (root_task_group_empty())
return;
- now = cpu_clock(raw_smp_processor_id());
+ now = local_clock();
elapsed = now - sd->last_update;
if (elapsed >= (s64)(u64)sysctl_sched_shares_ratelimit) {
Index: linux-2.6/kernel/sched_clock.c
===================================================================
--- linux-2.6.orig/kernel/sched_clock.c
+++ linux-2.6/kernel/sched_clock.c
@@ -249,6 +249,18 @@ unsigned long long cpu_clock(int cpu)
return clock;
}
+unsigned long long local_clock(void)
+{
+ unsigned long long clock;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ clock = sched_clock_cpu(smp_processor_id());
+ local_irq_restore(flags);
+
+ return clock;
+}
+
#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */
void sched_clock_init(void)
@@ -264,12 +276,17 @@ u64 sched_clock_cpu(int cpu)
return sched_clock();
}
-
unsigned long long cpu_clock(int cpu)
{
return sched_clock_cpu(cpu);
}
+unsigned long long local_clock(void)
+{
+ return sched_clock_cpu(0);
+}
+
#endif /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */
EXPORT_SYMBOL_GPL(cpu_clock);
+EXPORT_SYMBOL_GPL(local_clock);
Index: linux-2.6/kernel/trace/trace_clock.c
===================================================================
--- linux-2.6.orig/kernel/trace/trace_clock.c
+++ linux-2.6/kernel/trace/trace_clock.c
@@ -56,7 +56,7 @@ u64 notrace trace_clock_local(void)
*/
u64 notrace trace_clock(void)
{
- return cpu_clock(raw_smp_processor_id());
+ return local_clock();
}
Should I apply it first and then your today's patch or only the today's
patch?
Regards,
Piotr Hosowicz
--
Szef TVN24 do dziennikarzy: Kochani, przez dwa lata waliliśmy w obóz
rządzący. Tak dalej byc nie może. Jesteśmy telewizją niezależną i to
zobowiązuje. Teraz będziemy kopać w opozycję.
NP: Mark Knopfler - Hard Shoulder
NB: 2.6.34-20100527-2020-gitt-revtd
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