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Tue, 28 Jan 2025 10:54:12 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 640E4201EE; Tue, 28 Jan 2025 10:54:12 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E2DA7201EC; Tue, 28 Jan 2025 10:54:11 +0000 (GMT) Received: from [9.152.222.93] (unknown [9.152.222.93]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 28 Jan 2025 10:54:11 +0000 (GMT) Message-ID: Date: Tue, 28 Jan 2025 11:54:11 +0100 Precedence: bulk X-Mailing-List: linux-toolchains@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 19/39] unwind_user/sframe: Add support for reading .sframe contents To: Andrii Nakryiko , Josh Poimboeuf Cc: x86@kernel.org, Peter Zijlstra , Steven Rostedt , Ingo Molnar , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, Indu Bhagat , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , linux-perf-users@vger.kernel.org, Mark Brown , linux-toolchains@vger.kernel.org, Jordan Rome , Sam James , linux-trace-kernel@vger.kernel.org, Mathieu Desnoyers , Florian Weimer , Andy Lutomirski , Masami Hiramatsu , Weinan Liu References: <77c0d1ec143bf2a53d66c4ecb190e7e0a576fbfd.1737511963.git.jpoimboe@kernel.org> <20250124214107.ycccp4gapbdudzux@jpoimboe> From: Jens Remus Content-Language: en-US Organization: IBM Deutschland Research & Development GmbH In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: AXIQR8knhemm6G70G5RyZ_gr5iBVy9i5 X-Proofpoint-ORIG-GUID: EXUZoO8Jxqim8bKyyJptyCnarRLu770P X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-01-28_03,2025-01-27_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 impostorscore=0 lowpriorityscore=0 adultscore=0 clxscore=1015 priorityscore=1501 mlxlogscore=732 bulkscore=0 suspectscore=0 malwarescore=0 spamscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2411120000 definitions=main-2501280077 On 28.01.2025 01:39, Andrii Nakryiko wrote: > On Fri, Jan 24, 2025 at 1:41 PM Josh Poimboeuf wrote: >> On Fri, Jan 24, 2025 at 10:02:46AM -0800, Andrii Nakryiko wrote: >>> On Tue, Jan 21, 2025 at 6:32 PM Josh Poimboeuf wrote: >>>> + fre_addr = sec->fres_start + fde->fres_off; >>>> + >>>> + for (i = 0; i < fde->fres_num; i++) { >>> >>> why not binary search? seem more logical to guard against cases with >>> lots of FREs and be pretty fast in common case anyways. >> >> That would be nice, but the FREs are variable-sized and you don't know >> how big one is until you start reading it. > > ah, another non-obvious thing, yeah... do you think it's worth fixing > this and making FREs binary searchable in v3? > > Indu, do you have some stats on distribution of FRE count per FDE in practice? > > Tbh, FRE format is bothering me quite a lot... but let's discuss that > in another thread with you and Indu I would be interested to be part of that discussion. I could share some preliminary stats from my s390 work. Thanks and regards, Jens -- Jens Remus Linux on Z Development (D3303) +49-7031-16-1128 Office jremus@de.ibm.com IBM IBM Deutschland Research & Development GmbH; Vorsitzender des Aufsichtsrats: Wolfgang Wendt; Geschäftsführung: David Faller; Sitz der Gesellschaft: Böblingen; Registergericht: Amtsgericht Stuttgart, HRB 243294 IBM Data Privacy Statement: https://www.ibm.com/privacy/