From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v11 7/7] arm: pmu: Add PMU definitions for cores not initially online
Date: Thu, 15 Dec 2016 17:08:11 +0000 [thread overview]
Message-ID: <20161215170810.GJ10481@arm.com> (raw)
In-Reply-To: <457894f4-67f8-9d32-ee8b-5a34e9a21488@arm.com>
On Tue, Dec 06, 2016 at 11:56:56AM -0600, Jeremy Linton wrote:
> Hi,
>
> On 12/06/2016 09:21 AM, Will Deacon wrote:
> >On Fri, Dec 02, 2016 at 12:56:01PM -0600, Jeremy Linton wrote:
> >>ACPI CPUs aren't associated with a PMU until they have been put
> >>online. This means that we potentially have to update a PMU
> >>definition the first time a CPU is hot added to the machine.
> >>
> >>Signed-off-by: Jeremy Linton <jeremy.linton@arm•com>
> >>---
> >> drivers/perf/arm_pmu.c | 38 ++++++++++++++++++++++++++++++++++++--
> >> include/linux/perf/arm_pmu.h | 4 ++++
> >> 2 files changed, 40 insertions(+), 2 deletions(-)
> >>
> >>diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
> >>index fa40294..4abb2fe 100644
> >>--- a/drivers/perf/arm_pmu.c
> >>+++ b/drivers/perf/arm_pmu.c
> >>@@ -711,6 +711,30 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler)
> >> return 0;
> >> }
> >>
> >>+static DEFINE_SPINLOCK(arm_pmu_resource_lock);
> >
> >Why do you need this spinlock? The hotplug notifiers are serialised afaik,
> >and you don't take it anywhere else.
>
> Well, I assumed they were serialized, but then I went looking for a
> guarantee and couldn't find one specific to the notifiers, even though the
> previous lock was removed.
They should be serialised either by virtue of them all running off the back
of a single CPU (because the hotplug thread hasn't yet been created), or
by the st->done completion for the hotplug work threads.
Will
prev parent reply other threads:[~2016-12-15 17:08 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-02 18:55 [PATCH v11 0/7] Enable PMUs in ACPI systems Jeremy Linton
2016-12-02 18:55 ` [PATCH v11 1/7] arm64: Rename the common MADT parse routine Jeremy Linton
2016-12-02 18:55 ` [PATCH v11 2/7] arm: arm64: Add routine to determine cpuid of other cpus Jeremy Linton
2016-12-02 18:55 ` [PATCH v11 3/7] arm64: pmu: Cache PMU interrupt numbers from MADT parse Jeremy Linton
2016-12-02 18:55 ` [PATCH v11 4/7] arm: arm64: pmu: Assign platform PMU CPU affinity Jeremy Linton
2016-12-02 18:55 ` [PATCH v11 5/7] arm64: pmu: Detect multiple generic PMUs and append counter Jeremy Linton
2016-12-02 18:56 ` [PATCH v11 6/7] arm64: pmu: Detect and enable multiple PMUs in an ACPI system Jeremy Linton
2016-12-02 18:56 ` [PATCH v11 7/7] arm: pmu: Add PMU definitions for cores not initially online Jeremy Linton
2016-12-06 15:21 ` Will Deacon
2016-12-06 17:56 ` Jeremy Linton
2016-12-07 11:08 ` Mark Rutland
2016-12-15 17:08 ` Will Deacon [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20161215170810.GJ10481@arm.com \
--to=will.deacon@arm$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox