From: Shrikanth Hegde <sshegde@linux•ibm.com>
To: "Nysal Jan K.A." <nysal@linux•ibm.com>
Cc: Michael Ellerman <mpe@ellerman•id.au>,
linuxppc-dev@lists•ozlabs.org, linux-kernel@vger•kernel.org,
Madhavan Srinivasan <maddy@linux•ibm.com>,
Christophe Leroy <christophe.leroy@csgroup•eu>,
Nicholas Piggin <npiggin@gmail•com>
Subject: Re: [PATCH v2] powerpc/qspinlock: Add spinlock contention tracepoint
Date: Fri, 1 Aug 2025 22:12:00 +0530 [thread overview]
Message-ID: <322f02ee-4de9-4b1c-9727-409eb50c21fe@linux.ibm.com> (raw)
In-Reply-To: <20250731061856.1858898-1-nysal@linux.ibm.com>
On 7/31/25 11:48, Nysal Jan K.A. wrote:
> Add a lock contention tracepoint in the queued spinlock slowpath.
> Also add the __lockfunc annotation so that in_lock_functions()
> works as expected.
>
There is bit of pure code movement. Given that is small, single patch is fine.
> Signed-off-by: Nysal Jan K.A. <nysal@linux•ibm.com>
Tried the patch and able to see tracepoints.
Reviewed-by: Shrikanth Hegde <sshegde@linux•ibm.com>
> ---
> arch/powerpc/lib/qspinlock.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/lib/qspinlock.c b/arch/powerpc/lib/qspinlock.c
> index bcc7e4dff8c3..95ab4cdf582e 100644
> --- a/arch/powerpc/lib/qspinlock.c
> +++ b/arch/powerpc/lib/qspinlock.c
> @@ -9,6 +9,7 @@
> #include <linux/sched/clock.h>
> #include <asm/qspinlock.h>
> #include <asm/paravirt.h>
> +#include <trace/events/lock.h>
>
> #define MAX_NODES 4
>
> @@ -708,26 +709,26 @@ static __always_inline void queued_spin_lock_mcs_queue(struct qspinlock *lock, b
> qnodesp->count--;
> }
>
> -void queued_spin_lock_slowpath(struct qspinlock *lock)
> +void __lockfunc queued_spin_lock_slowpath(struct qspinlock *lock)
> {
> + trace_contention_begin(lock, LCB_F_SPIN);
> /*
> * This looks funny, but it induces the compiler to inline both
> * sides of the branch rather than share code as when the condition
> * is passed as the paravirt argument to the functions.
> */
> if (IS_ENABLED(CONFIG_PARAVIRT_SPINLOCKS) && is_shared_processor()) {
> - if (try_to_steal_lock(lock, true)) {
> + if (try_to_steal_lock(lock, true))
> spec_barrier();
> - return;
> - }
> - queued_spin_lock_mcs_queue(lock, true);
> + else
> + queued_spin_lock_mcs_queue(lock, true);
> } else {
> - if (try_to_steal_lock(lock, false)) {
> + if (try_to_steal_lock(lock, false))
> spec_barrier();
> - return;
> - }
> - queued_spin_lock_mcs_queue(lock, false);
> + else
> + queued_spin_lock_mcs_queue(lock, false);
> }
> + trace_contention_end(lock, 0);
> }
> EXPORT_SYMBOL(queued_spin_lock_slowpath);
>
>
next prev parent reply other threads:[~2025-08-01 16:42 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-25 8:14 [PATCH] powerpc/qspinlock: Add spinlock contention tracepoint Nysal Jan K.A.
2025-07-30 6:46 ` Christophe Leroy
2025-07-30 8:33 ` Nysal Jan K.A.
2025-07-30 10:46 ` samir
2025-07-31 6:18 ` [PATCH v2] " Nysal Jan K.A.
2025-08-01 16:42 ` Shrikanth Hegde [this message]
2025-09-06 10:07 ` Madhavan Srinivasan
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