| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <1276166813.2077.96.camel@twins>
Date: Thu, 10 Jun 2010 12:46:53 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Paul Mackerras <paulus@...ba.org>,
Stephane Eranian <eranian@...gle.com>,
Cyrill Gorcunov <gorcunov@...il.com>,
Zhang Yanmin <yanmin_zhang@...ux.intel.com>,
Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH 1/5] perf: Provide a proper stop action for software
events
On Thu, 2010-06-10 at 05:49 +0200, Frederic Weisbecker wrote:
> In order to introduce new context exclusions, software events will
> have to eventually stop when needed. We'll want perf_event_stop() to
> act on every events.
>
> To achieve this, remove the stub stop/start pmu callbacks of software
> and tracepoint events.
>
> This may even optimize the case of hardware and software events
> running at the same time: now we only stop/start all hardware
> events if we reset a hardware event period, not anymore with
> software events.
>
> Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
> Cc: Ingo Molnar <mingo@...e.hu>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: Paul Mackerras <paulus@...ba.org>
> Cc: Stephane Eranian <eranian@...gle.com>
> Cc: Cyrill Gorcunov <gorcunov@...il.com>
> Cc: Zhang Yanmin <yanmin_zhang@...ux.intel.com>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> ---
> kernel/perf_event.c | 29 ++++++++++++++++-------------
> 1 files changed, 16 insertions(+), 13 deletions(-)
>
> diff --git a/kernel/perf_event.c b/kernel/perf_event.c
> index c772a3d..5c004f7 100644
> --- a/kernel/perf_event.c
> +++ b/kernel/perf_event.c
> @@ -1541,11 +1541,23 @@ static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count)
> hwc->sample_period = sample_period;
>
> if (local64_read(&hwc->period_left) > 8*sample_period) {
> - perf_disable();
> - perf_event_stop(event);
> + bool software_event = is_software_event(event);
> +
> + /*
> + * Only hardware events need their irq period to be
> + * reprogrammed
> + */
> + if (!software_event) {
> + perf_disable();
> + perf_event_stop(event);
> + }
> +
> local64_set(&hwc->period_left, 0);
> - perf_event_start(event);
> - perf_enable();
> +
> + if (!software_event) {
> + perf_event_start(event);
> + perf_enable();
> + }
> }
> }
>
> @@ -4286,16 +4298,9 @@ static void perf_swevent_void(struct perf_event *event)
> {
> }
>
> -static int perf_swevent_int(struct perf_event *event)
> -{
> - return 0;
> -}
> -
> static const struct pmu perf_ops_generic = {
> .enable = perf_swevent_enable,
> .disable = perf_swevent_disable,
> - .start = perf_swevent_int,
> - .stop = perf_swevent_void,
> .read = perf_swevent_read,
> .unthrottle = perf_swevent_void, /* hwc->interrupts already reset */
> };
> @@ -4578,8 +4583,6 @@ static int swevent_hlist_get(struct perf_event *event)
> static const struct pmu perf_ops_tracepoint = {
> .enable = perf_trace_enable,
> .disable = perf_trace_disable,
> - .start = perf_swevent_int,
> - .stop = perf_swevent_void,
> .read = perf_swevent_read,
> .unthrottle = perf_swevent_void,
> };
I really don't like this.. we should be removing differences between
software and hardware pmu implementations, not add more :/
Something like the below would work, the only 'problem' is that it grows
hw_perf_event.
---
include/linux/perf_event.h | 1 +
kernel/perf_event.c | 27 ++++++++++++++++++---------
2 files changed, 19 insertions(+), 9 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 9073bde..2292659 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -531,6 +531,7 @@ struct hw_perf_event {
struct { /* software */
s64 remaining;
struct hrtimer hrtimer;
+ int stopped;
};
#ifdef CONFIG_HAVE_HW_BREAKPOINT
/* breakpoint */
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 403d180..14b691e 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4113,6 +4113,9 @@ static int perf_swevent_match(struct perf_event *event,
struct perf_sample_data *data,
struct pt_regs *regs)
{
+ if (event->hw.stopped)
+ return 0;
+
if (event->attr.type != type)
return 0;
@@ -4282,22 +4285,28 @@ static void perf_swevent_disable(struct perf_event *event)
hlist_del_rcu(&event->hlist_entry);
}
-static void perf_swevent_void(struct perf_event *event)
+static void perf_swevent_throttle(struct perf_event *event)
{
+ /* hwc->interrupts already reset */
}
-static int perf_swevent_int(struct perf_event *event)
+static int perf_swevent_start(struct perf_event *event)
{
- return 0;
+ event->hw.stopped = 0;
+}
+
+static void perf_swevent_throttle(struct perf_event *event)
+{
+ event->hw.stopped = 1;
}
static const struct pmu perf_ops_generic = {
.enable = perf_swevent_enable,
.disable = perf_swevent_disable,
- .start = perf_swevent_int,
- .stop = perf_swevent_void,
+ .start = perf_swevent_start,
+ .stop = perf_swevent_stop,
.read = perf_swevent_read,
- .unthrottle = perf_swevent_void, /* hwc->interrupts already reset */
+ .unthrottle = perf_swevent_throttle,
};
/*
@@ -4578,10 +4587,10 @@ static int swevent_hlist_get(struct perf_event *event)
static const struct pmu perf_ops_tracepoint = {
.enable = perf_trace_enable,
.disable = perf_trace_disable,
- .start = perf_swevent_int,
- .stop = perf_swevent_void,
+ .start = perf_swevent_start,
+ .stop = perf_swevent_stop,
.read = perf_swevent_read,
- .unthrottle = perf_swevent_void,
+ .unthrottle = perf_swevent_throttle,
};
static int perf_tp_filter_match(struct perf_event *event,
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists