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Tue, 22 Sep 2026 18:22:56 +0000 (GMT) Received: from osiris (unknown [9.111.71.5]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTPS; Tue, 22 Sep 2026 18:22:56 +0000 (GMT) Date: Tue, 22 Sep 2026 20:22:55 +0200 From: Heiko Carstens To: Mete Durlu Cc: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , Peter Zijlstra , Mark Rutland , Juergen Christ , Ilya Leoshkevich , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH v4 00/11] s390: More this_cpu_*() changes Message-ID: <20260922182255.26236Cc2-hca@linux.ibm.com> References: <20260921155806.2447506-1-hca@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: X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: R3Rm1nbfO4gltRVUTXODtSL29oCz_OMz X-Authority-Analysis: v=2.4 cv=I43w19gg c=1 sm=1 tr=0 ts=6ab2c787 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=_IjnK-qXvPJbhhBBUg8A:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTIyMDI2NSBTYWx0ZWRfX+6vkDMfq2RGS 2YzxSdoAZZrHvqgIs9aQI1T6zHOeNAJ17TiOclbjKaiG3YaLm3DmCpJtiMilHDTNCsvEQJadtqu GHEN/Kayz2sY7oOE/AWR6aDDl/BMTcJnJ9CgY6eElFKNDj0tkL3jlJtbgdaaREwVdzk1bt0kwDZ kFo/BbqAffZW2qPylW4Oe7U0aYfvK9/nfyC+LO0gShFoQ6BqyvMBxZnMkCMppdhVRJUwXTfz8xJ 2G+Mu4vhmVzPVdt7m0Kfjc7w6lmkoL3PkjUo55D1s4Y5gR4qAyfTuwD0bXr4IKBI27gNHpyCXJt DoqKQrgw9vSfTjmFkS071t76NUIz0FR7nsBI0Mir9eSndNwlBAHt6nGilPECAb5da62mibCopMG ytOcaBkot5YWQdHk9TFz0XMVi7rNCHlEk09hCgKQtTmMytaNXZv9NdELz3ECXD1bdj9NAlCButo MgqjLPH3utrXJfHprTQ== X-Proofpoint-Spam-Info: AW1haW4tMjYwOTIyMDI2NSBTYWx0ZWRfX+BQM/0j2giAe qSD67oDJXV41kOb4RMiJxlHS6z739h5DErSXwfHdUsrqnGnrJqvRoiK0ReV2Kv5+LqMLtAlNltx 0/bWxbTb+sOsAyaSX5U75aDE0vX9kY8= X-Proofpoint-GUID: R3Rm1nbfO4gltRVUTXODtSL29oCz_OMz 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=2026-09-22_03,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 clxscore=1015 adultscore=0 suspectscore=0 impostorscore=0 lowpriorityscore=0 bulkscore=0 phishscore=0 priorityscore=1501 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609220265 On Tue, Sep 22, 2026 at 05:37:14PM +0200, Mete Durlu wrote: > On 21/09/2026 17:57, Heiko Carstens wrote: > [..snip..] > > The only non-trivial patch is the last one, which converts s390's > > this_cpu_*() operations to use a similar scheme like Mark Rutland > > provided it for arm64 [1]. This allows to simplify the irq entry and exit > > path, however at the cost of slightly worse code for this_cpu_*() > > operations. ... > Hi all, > > I did some benchmarking for this patch series. > > Used a shared LPAR with 24 CPUs (12 cores w SMT2). > > Base commit: f0100363d8c3 ("Merge tag 'xfs-fixes-7.3-rc5' of > gitolite.kernel.org:/pub/scm/fs/xfs/xfs-linux") > > Some of the benchmark runs show +-5% standard deviation which can > be attributed to s390 being a virtualized system. Each run has been > repeated five times to circumvent the effects of standard deviation. > (In the odd case where baseline has -5% and patched run has +5% > deviation, the comparison can show ~+10% improvements which is highly > misleading). > > Overall, the benchmarks do not show any real difference between baseline > and patched kernels; Mete, thanks a lot for running the benchmarks! This confirms that we can move forward including the last patch of this series.