From: Adrian Hunter <adrian.hunter@intel.com>
To: Leo Yan <leo.yan@linaro.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Mike Leach <mike.leach@linaro.org>,
Andi Kleen <ak@linux.intel.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 5/8] perf auxtrace: Change to use SMP memory barriers
Date: Mon, 7 Jun 2021 13:02:50 +0300 [thread overview]
Message-ID: <f3215353-0b01-368d-56ab-00d1335639b5@intel.com> (raw)
In-Reply-To: <20210602103007.184993-6-leo.yan@linaro.org>
On 2/06/21 1:30 pm, Leo Yan wrote:
> The kernel and the userspace tool can access the AUX ring buffer head
> and tail from different CPUs, thus SMP class of barriers are required
> on SMP system.
>
> This patch changes to use SMP barriers to replace mb() and rmb()
> barriers.
>
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
> tools/perf/util/auxtrace.h | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
> index a4fbb33b7245..42b7ef811bde 100644
> --- a/tools/perf/util/auxtrace.h
> +++ b/tools/perf/util/auxtrace.h
> @@ -444,7 +444,7 @@ static inline u64 auxtrace_mmap__read_snapshot_head(struct auxtrace_mmap *mm)
> u64 head = READ_ONCE(pc->aux_head);
>
> /* Ensure all reads are done after we read the head */
> - rmb();
> + smp_rmb();
> return head;
> }
>
> @@ -458,7 +458,7 @@ static inline u64 auxtrace_mmap__read_head(struct auxtrace_mmap *mm)
> #endif
>
> /* Ensure all reads are done after we read the head */
> - rmb();
> + smp_rmb();
> return head;
> }
>
> @@ -470,7 +470,7 @@ static inline void auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail)
> #endif
>
> /* Ensure all reads are done before we write the tail out */
> - mb();
> + smp_mb();
> #if BITS_PER_LONG == 64 || !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
> pc->aux_tail = tail;
> #else
>
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next prev parent reply other threads:[~2021-06-07 10:37 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-02 10:29 [PATCH v2 0/8] perf: Refine barriers for AUX ring buffer Leo Yan
2021-06-02 10:30 ` [PATCH v2 1/8] perf/ring_buffer: Add comment for barriers on " Leo Yan
2021-06-07 15:27 ` Peter Zijlstra
2021-06-02 10:30 ` [PATCH v2 2/8] coresight: tmc-etr: Add barrier after updating " Leo Yan
2021-06-02 10:30 ` [PATCH v2 3/8] coresight: tmc-etf: Add comment for store ordering Leo Yan
2021-06-02 10:30 ` [PATCH v2 4/8] perf/x86: Add barrier after updating bts Leo Yan
2021-06-07 15:29 ` Peter Zijlstra
2021-06-02 10:30 ` [PATCH v2 5/8] perf auxtrace: Change to use SMP memory barriers Leo Yan
2021-06-07 10:02 ` Adrian Hunter [this message]
2021-06-07 15:29 ` Peter Zijlstra
2021-06-08 16:45 ` Arnaldo Carvalho de Melo
2021-06-02 10:30 ` [PATCH v2 6/8] perf auxtrace: Drop legacy __sync functions Leo Yan
2021-06-02 10:47 ` Adrian Hunter
2021-06-02 11:16 ` Leo Yan
2021-06-02 11:21 ` Adrian Hunter
2021-06-02 13:01 ` Leo Yan
2021-06-02 10:30 ` [PATCH v2 7/8] perf auxtrace: Use WRITE_ONCE() for updating aux_tail Leo Yan
2021-06-07 10:03 ` Adrian Hunter
2021-06-07 15:31 ` Peter Zijlstra
2021-06-08 17:04 ` Arnaldo Carvalho de Melo
2021-06-09 0:21 ` Leo Yan
2021-06-02 10:30 ` [PATCH v2 8/8] perf record: Directly bail out for compat case Leo Yan
2021-06-02 11:18 ` Adrian Hunter
2021-06-02 12:38 ` Leo Yan
2021-06-07 10:23 ` Adrian Hunter
2021-06-07 15:09 ` Leo Yan
2021-06-09 8:23 ` Adrian Hunter
2021-06-09 8:57 ` Leo Yan
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