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Wed, 23 Sep 2026 06:02:38 +0000 (GMT) Received: from [9.111.22.84] (unknown [9.111.22.84]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 23 Sep 2026 06:02:38 +0000 (GMT) Message-ID: <7a05f81f-1cd0-4ef0-a1bc-424b19f04626@linux.ibm.com> Date: Wed, 23 Sep 2026 08:02:37 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 00/11] s390: More this_cpu_*() changes To: Heiko Carstens 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 References: <20260921155806.2447506-1-hca@linux.ibm.com> <20260922182255.26236Cc2-hca@linux.ibm.com> Content-Language: en-US From: Mete Durlu In-Reply-To: <20260922182255.26236Cc2-hca@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: Oa1qwrk0hedGmGrucZJmB8_nWKusJJmx X-Authority-Analysis: v=2.4 cv=EOCTQFZC c=1 sm=1 tr=0 ts=6ab36b83 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=lJ8Ht4UjfrDHC3yQZS8A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTIzMDAyMiBTYWx0ZWRfX1SX6NjbDNRuj z1lyrXOojs5apO29u9XtCTjnmOg7XITd05JrSo/lLJgO5HP6XH7lqkVDsNdzwPsXgCjM2/wKh5q guxKZ4R6O7tF2EJjWMlRGgnTX9i8QoY= X-Proofpoint-GUID: Oa1qwrk0hedGmGrucZJmB8_nWKusJJmx X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTIzMDAyMiBTYWx0ZWRfX0LYocv9dYVN4 IGXMFexcotpC+lMoYOU6ZmqJgkIPnbMNvY2HmG9ltH265tpuzUXIOZZKTbmoAnPCZ41zGIOu/BM QLvP6XWvODUPmhvvc8U3QJAHRUlsJzvTXz5CBdVjS+mA5rqlK4SyS9M+UIWCH49cF4usl6Ecr8r oGqa/bXJ7UBEYVeanK9FroFnuBAhJfg/qHdbKltpZsPrmnV2hNajJVGz6ff96gdCJ+3U91Ybpm3 zBpy++82fk3+1nN1swb6xCclZNbHhhYzvKvzErNb1SXavSjwyV82op3W82sIOzwcc0Yp/uoczkp OTnblBrQ9FctlNlAyqJJSmwJ9TW0IplGs+PO1V0MFsJ8m0/p35qZLXSaIr+OSEz5+hr8wrKCh9i B9mq1k6MIXisNg92N6TZYTsS1q5iMavcfGhaMqsF7ZS172p9N4MVXLVeaw8txf6tx9DLAwcAxzq otak1IcelA5UUNnrIZw== 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=2026-09-23_02,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 phishscore=0 priorityscore=1501 clxscore=1015 spamscore=0 adultscore=0 impostorscore=0 lowpriorityscore=0 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609230022 On 22/09/2026 20:22, Heiko Carstens wrote: > 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. I also gave it a spin on a zVM instance. Results are quite similar. FWIW, here is my tested by; Tested-by: Mete Durlu