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Mon, 14 Sep 2026 17:02:54 +0000 (GMT) Received: from osiris (unknown [9.87.150.220]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTPS; Mon, 14 Sep 2026 17:02:54 +0000 (GMT) Date: Mon, 14 Sep 2026 19:02:53 +0200 From: Heiko Carstens To: Jan Polensky Cc: gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ciunas@linux.ibm.com, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] s390/rwlock: Add contention tracepoints to rwlock slowpath Message-ID: <20260914170253.14910D83-hca@linux.ibm.com> References: <20260908135843.1384367-1-japo@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260908135843.1384367-1-japo@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-GUID: QgubwiQRHltJ97dq5ZBuBi4FDk_ia1vJ X-Proofpoint-Spam-Info: AW1haW4tMjYwOTE0MDI0MSBTYWx0ZWRfX4tJO5h1ROpsS 4lK/8Ijne0Q6HXl1LyFyeTYIu8P1xQVV5/rYNPw+YBtkn+9icNykLX33iZHORJXNbL4kj9tiAbA k2IpneO6ZQGbeAY88qdbmpRaL/8WakE= X-Authority-Analysis: v=2.4 cv=cvgOAF4i c=1 sm=1 tr=0 ts=6aa828c4 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=VFibKQHTiDGcZmGrcJYA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-ORIG-GUID: QgubwiQRHltJ97dq5ZBuBi4FDk_ia1vJ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTE0MDI0MSBTYWx0ZWRfX83maR1TKlfZD 7/nosdhu3kyoufQDv2jxRvDgWxGk3GUMvJLoxekLOXN1FwxXsW6LoC3ZBDX8NarytP+ZYdX64Ov S4VKEl2RgEIWP+JrZKMEGn4qEdbtw3ubwFPYCY4mPXoooH2iCQndOAzX4mhRac1I+SGF1pWr8Qk RYXX5VGIrUuWUOohBrZY3al61lhL/agAJ7KD3HWKW1WncfV7dY1+v3CqiMgIr2ONmqbPrSscsKq vIT4JvnaiZz06/SfFQywiKltZhM5P6xvmqzGc9UYiC2HJXSDacB5tmpl5qsK7c+ZDcJIGgmikq2 vdRM6qjoGHrfmtfTnvppNWdgovGlbSqXjyAxZHkSMs7z7uBpRCrwZo/9BClC97f7WyN1R3MWXX4 5AOsrGOpzWorXnNef/p2TPMb/2Mba9xf/dT+KgzA7L21sAgetbnoHfqNLAhXC0GQqJS4zPCSIwR ZYzqJaYiWO4Azk2JLqw== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-14_03,2026-09-14_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 lowpriorityscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 bulkscore=0 impostorscore=0 phishscore=0 spamscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609140241 On Tue, Sep 08, 2026 at 03:58:43PM +0200, Jan Polensky wrote: > Instrument arch_read_lock_wait() and arch_write_lock_wait() with > trace_contention_begin() and trace_contention_end(). > > These tracepoints are used by lock contention analysis tools such as > perf lock contention to identify contended rwlocks and measure wait > times. The generic implementation in kernel/locking/qrwlock.c already > emits the same events from its read and write slowpaths. > > For arch_read_lock_wait(), the in_interrupt() fast-path is intentionally > left outside the tracepoint scope. That path spins without entering the > wait queue, so it does not represent queue-based contention and its > duration is not comparable to the normal slowpath. This matches the > behaviour of queued_read_lock_slowpath() in qrwlock.c. > > The include for is already present from > commit ffa796cc1f45 ("s390/spinlock: Add contention tracepoints to > lock slowpath"). > > Signed-off-by: Jan Polensky > --- > v1 -> v2: > - Fix tracepoint placement in arch_read_lock_wait() to avoid recursion deadlocks. > > arch/s390/lib/spinlock.c | 4 ++++ > 1 file changed, 4 insertions(+) Applied, thanks!