From: Peter Zijlstra <peterz@infradead.org>
To: Don Zickus <dzickus@redhat.com>
Cc: dave.hansen@linux.intel.com, eranian@google.com,
ak@linux.intel.com, jmario@redhat.com,
linux-kernel@vger.kernel.org, acme@infradead.org
Subject: Re: x86, perf: throttling issues with long nmi latencies
Date: Tue, 15 Oct 2013 16:32:27 +0200 [thread overview]
Message-ID: <20131015143227.GY26785@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20131015130226.GX26785@twins.programming.kicks-ass.net>
This one seems to actually work and is somewhat simpler.
---
arch/x86/kernel/cpu/perf_event_intel_ds.c | 31 +++++++++++++++++++------------
1 file changed, 19 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 32e9ed81cd00..9c7e043f8514 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -722,6 +722,8 @@ void intel_pmu_pebs_disable_all(void)
wrmsrl(MSR_IA32_PEBS_ENABLE, 0);
}
+static DEFINE_PER_CPU(u8 [PAGE_SIZE], insn_page);
+
static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
@@ -729,6 +731,7 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs)
unsigned long old_to, to = cpuc->lbr_entries[0].to;
unsigned long ip = regs->ip;
int is_64bit = 0;
+ void *kaddr;
/*
* We don't need to fixup if the PEBS assist is fault like
@@ -763,29 +766,33 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs)
return 1;
}
+ if (!kernel_ip(ip)) {
+ int size, bytes;
+ u8 *buf = &__get_cpu_var(insn_page[0]);
+
+ size = ip - to; /* Must be le than PAGE_SIZE, see above */
+ bytes = copy_from_user_nmi(buf, (void __user *)to, size);
+ if (bytes != size)
+ return 0;
+
+ kaddr = buf;
+ } else {
+ kaddr = (void *)to;
+ }
+
do {
struct insn insn;
- u8 buf[MAX_INSN_SIZE];
- void *kaddr;
old_to = to;
- if (!kernel_ip(ip)) {
- int bytes, size = MAX_INSN_SIZE;
-
- bytes = copy_from_user_nmi(buf, (void __user *)to, size);
- if (bytes != size)
- return 0;
-
- kaddr = buf;
- } else
- kaddr = (void *)to;
#ifdef CONFIG_X86_64
is_64bit = kernel_ip(to) || !test_thread_flag(TIF_IA32);
#endif
insn_init(&insn, kaddr, is_64bit);
insn_get_length(&insn);
+
to += insn.length;
+ kaddr += insn.length;
} while (to < ip);
if (to == ip) {
next prev parent reply other threads:[~2013-10-15 14:32 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-14 20:35 x86, perf: throttling issues with long nmi latencies Don Zickus
2013-10-14 21:28 ` Andi Kleen
2013-10-15 10:14 ` Peter Zijlstra
2013-10-15 13:02 ` Peter Zijlstra
2013-10-15 14:32 ` Peter Zijlstra [this message]
2013-10-15 15:07 ` Peter Zijlstra
2013-10-15 15:41 ` Don Zickus
2013-10-16 10:57 ` [PATCH] perf, x86: Optimize intel_pmu_pebs_fixup_ip() Peter Zijlstra
2013-10-16 12:46 ` Don Zickus
2013-10-16 13:31 ` Peter Zijlstra
2013-10-16 13:54 ` Don Zickus
2013-10-17 11:21 ` Peter Zijlstra
2013-10-17 13:33 ` Peter Zijlstra
2013-10-29 14:07 ` [tip:perf/urgent] perf/x86: Fix NMI measurements tip-bot for Peter Zijlstra
2013-10-16 20:52 ` [PATCH] perf, x86: Optimize intel_pmu_pebs_fixup_ip() Andi Kleen
2013-10-16 21:03 ` Peter Zijlstra
2013-10-16 23:07 ` Peter Zijlstra
2013-10-17 9:41 ` Peter Zijlstra
2013-10-17 16:00 ` Don Zickus
2013-10-17 16:04 ` Don Zickus
2013-10-17 16:30 ` Peter Zijlstra
2013-10-17 18:26 ` Linus Torvalds
2013-10-17 21:08 ` Peter Zijlstra
2013-10-17 21:11 ` Peter Zijlstra
2013-10-17 22:01 ` Peter Zijlstra
2013-10-17 22:27 ` Linus Torvalds
2013-10-22 21:12 ` Peter Zijlstra
2013-10-23 7:09 ` Linus Torvalds
2013-10-23 20:48 ` Peter Zijlstra
2013-10-24 10:52 ` Peter Zijlstra
2013-10-24 13:47 ` Don Zickus
2013-10-24 14:06 ` Peter Zijlstra
2013-10-25 16:33 ` Don Zickus
2013-10-25 17:03 ` Peter Zijlstra
2013-10-26 10:36 ` Ingo Molnar
2013-10-28 13:19 ` Don Zickus
2013-10-29 14:08 ` [tip:perf/core] perf/x86: Further optimize copy_from_user_nmi() tip-bot for Peter Zijlstra
2013-10-23 7:44 ` [PATCH] perf, x86: Optimize intel_pmu_pebs_fixup_ip() Ingo Molnar
2013-10-17 14:49 ` Don Zickus
2013-10-17 14:51 ` Peter Zijlstra
2013-10-17 15:03 ` Don Zickus
2013-10-17 15:09 ` Peter Zijlstra
2013-10-17 15:11 ` Peter Zijlstra
2013-10-17 16:50 ` [tip:perf/core] perf/x86: " tip-bot for Peter Zijlstra
2013-10-15 16:22 ` x86, perf: throttling issues with long nmi latencies Don Zickus
2013-10-15 14:36 ` Don Zickus
2013-10-15 14:39 ` Peter Zijlstra
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