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To: Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, =?UTF-8?Q?Andr=C3=A9_Almeida?= , Darren Hart , Davidlohr Bueso , Ingo Molnar , Juri Lelli , Peter Zijlstra , Thomas Gleixner , Valentin Schneider , Waiman Long , "Liang, Kan" , Adrian Hunter , Alexander Shishkin , Arnaldo Carvalho de Melo , Ian Rogers , Jiri Olsa , Mark Rutland , Namhyung Kim , linux-perf-users@vger.kernel.org References: <20250407155742.968816-1-bigeasy@linutronix.de> <20250407155742.968816-20-bigeasy@linutronix.de> <20250410152841.KypBTUMq@linutronix.de> From: Shrikanth Hegde Content-Language: en-US In-Reply-To: <20250410152841.KypBTUMq@linutronix.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: sLO1o9SBXaHS2NqkpNMkjUD7kKMwUt6O X-Proofpoint-GUID: cwdYC3Pp8-y04t_1GNsMfz48tD2g1RKt X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1095,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-04-10_04,2025-04-10_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 mlxscore=0 bulkscore=0 malwarescore=0 phishscore=0 mlxlogscore=999 adultscore=0 suspectscore=0 priorityscore=1501 spamscore=0 impostorscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2504100112 On 4/10/25 20:58, Sebastian Andrzej Siewior wrote: > On 2025-04-10 20:22:08 [+0530], Shrikanth Hegde wrote: >> Hi Sebastian. > Hi Shrikanth, > >> It would be good option for the application to decide if it needs this. > > You mean to have it as I introduced it here or something else? > as you have introduced it here. >> Using this option makes the perf regression goes away using previous number of buckets. > > Okay, good to know. You test this on on ppc64le? Yes. > >> Acked-by: Shrikanth Hegde >> >> base: >> ./perf bench futex hash >> Averaged 1556023 operations/sec (+- 0.08%), total secs = 10 <<-- 1.5M >> >> with series: >> ./perf bench futex hash -b32768 >> Averaged 126499 operations/sec (+- 0.41%), total secs = 10 <<-- .12M >> >> ./perf bench futex hash -Ib32768 >> Averaged 1549339 operations/sec (+- 0.08%), total secs = 10 <<-- 1.5M > Thank you for testing. > … >> nit: Does it makes sense to split this patch into futex and perf? > > First I wanted to figure if we really do this. I have no idea if this > regression would show up in real world use case or just here as part of > the micro benchmark. > And if we do this, it would probably make sense to have one perf patch > which introduces -b & -I. And then figure out if the additional option > to prctl should be part of the resize patch or not. Probably we should > enforce 0/1 of arg4 from the beginning so maybe folding this in makes > sense. > ok. > Sebastian