Low Latency Tuning for Linux
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Kernel Boot-Time Tracing
Kernel Boot-time Tracing Linux Plumbers Conference 2019 - Tracing Track Masami Hiramatsu <[email protected]> Linaro, Ltd. Speaker Masami Hiramatsu - Working for Linaro and Linaro members - Tech Lead for a Landing team - Maintainer of Kprobes and related tracing features/tools Why Kernel Boot-time Tracing? Debug and analyze boot time errors and performance issues - Measure performance statistics of kernel boot - Analyze driver init failure - Debug boot up process - Continuously tracing from boot time etc. What We Have There are already many ftrace options on kernel command line ● Setup options (trace_options=) ● Output to printk (tp_printk) ● Enable events (trace_events=) ● Enable tracers (ftrace=) ● Filtering (ftrace_filter=,ftrace_notrace=,ftrace_graph_filter=,ftrace_graph_notrace=) ● Add kprobe events (kprobe_events=) ● And other options (alloc_snapshot, traceoff_on_warning, ...) See Documentation/admin-guide/kernel-parameters.txt Example of Kernel Cmdline Parameters In grub.conf linux /boot/vmlinuz-5.1 root=UUID=5a026bbb-6a58-4c23-9814-5b1c99b82338 ro quiet splash tp_printk trace_options=”sym-addr” trace_clock=global ftrace_dump_on_oops trace_buf_size=1M trace_event=”initcall:*,irq:*,exceptions:*” kprobe_event=”p:kprobes/myevent foofunction $arg1 $arg2;p:kprobes/myevent2 barfunction %ax” What Issues? Size limitation ● kernel cmdline size is small (< 256bytes) ● A half of the cmdline is used for normal boot Only partial features supported ● ftrace has too complex features for single command line ● per-event filters/actions, instances, histograms. Solutions? 1. Use initramfs - Too late for kernel boot time tracing 2. Expand kernel cmdline - It is not easy to write down complex tracing options on bootloader (Single line options is too simple) 3. Reuse structured boot time data (Devicetree) - Well documented, structured data -> V1 & V2 series based on this. Boot-time Trace: V1 and V2 series V1 and V2 series posted at June. -
Linux Perf Event Features and Overhead
Linux perf event Features and Overhead 2013 FastPath Workshop Vince Weaver http://www.eece.maine.edu/∼vweaver [email protected] 21 April 2013 Performance Counters and Workload Optimized Systems • With processor speeds constant, cannot depend on Moore's Law to deliver increased performance • Code analysis and optimization can provide speedups in existing code on existing hardware • Systems with a single workload are best target for cross- stack hardware/kernel/application optimization • Hardware performance counters are the perfect tool for this type of optimization 1 Some Uses of Performance Counters • Traditional analysis and optimization • Finding architectural reasons for slowdown • Validating Simulators • Auto-tuning • Operating System optimization • Estimating power/energy in software 2 Linux and Performance Counters • Linux has become the operating system of choice in many domains • Runs most of the Top500 list (over 90%) on down to embedded devices (Android Phones) • Until recently had no easy access to hardware performance counters, limiting code analysis and optimization. 3 Linux Performance Counter History • oprofile { system-wide sampling profiler since 2002 • perfctr { widely used general interface available since 1999, required patching kernel • perfmon2 { another general interface, included in kernel for itanium, made generic, big push for kernel inclusion 4 Linux perf event • Developed in response to perfmon2 by Molnar and Gleixner in 2009 • Merged in 2.6.31 as \PCL" • Unusual design pushes most functionality into kernel -
Steve French IBM – Linux Technology Center
IBM Server & Technology Group Linux Kernel Clients: A Year in Review “Man-Eating Seals of Antiquity” to “Sheep on Meth” Steve French IBM – Linux Technology Center Linux Technology Center © 2010 IBM Corporation SNIA SDC 2010 Legal Statement –This work represents the views of the author(s) and does not necessarily reflect the views of IBM Corporation –A full list of U.S. trademarks owned by IBM may be found at http://www.ibm.com/legal/copytrade.shtml. –Linux is a registered trademark of Linus Torvalds. –Other company, product, and service names may be trademarks or service marks of others. 2 IBM Linux Technology Center © 2010 IBM Corporation SNIA SDC 2010 Who am I? –Steve French ([email protected] or [email protected]) –Author and maintainer of Linux cifs vfs (for accessing Samba, Windows and various SMB/CIFS based NAS appliances) –Wrote initial SMB2 kernel client prototype –Member of the Samba team, coauthor of CIFS Technical Reference and former SNIA CIFS Working Group chair –Architect: Filesystems/NFS/Samba for IBM LTC IBM Linux Technology Center © 2010 IBM Corporation SNIA SDC 2010 • Last September Kernel version 2.6.31: • [Since 2.6.34] Now we have • “Man-Eating Seals of Antiquity” 2.6.36-rc4 – 2.6.31 came out on September 9th, 2009 • “Sheep on Meth” 4 IBM Linux Technology Center © 2010 IBM Corporation SNIA SDC 2010 Development on Linux kernel clients is very active • 187 kernel changesets for cifs since 2.6.31 (typical year) • But … improvements to related tools have accelerated dramatically: in a few month period early this year 100+ changesets in mount helper and related utilities were merged • And smb2 development accelerated … – A month after SambaXP last year, public git tree for smb2 development created on kernel.org – More than 130 kernel changesets for smb2 since January – SMB2 module now close to full function but 30% smaller (17188 lines of code, CIFS is now 24447 LOC). -
Hiding Process Memory Via Anti-Forensic Techniques
DIGITAL FORENSIC RESEARCH CONFERENCE Hiding Process Memory via Anti-Forensic Techniques By: Frank Block (Friedrich-Alexander Universität Erlangen-Nürnberg (FAU) and ERNW Research GmbH) and Ralph Palutke (Friedrich-Alexander Universität Erlangen-Nürnberg) From the proceedings of The Digital Forensic Research Conference DFRWS USA 2020 July 20 - 24, 2020 DFRWS is dedicated to the sharing of knowledge and ideas about digital forensics research. Ever since it organized the first open workshop devoted to digital forensics in 2001, DFRWS continues to bring academics and practitioners together in an informal environment. As a non-profit, volunteer organization, DFRWS sponsors technical working groups, annual conferences and challenges to help drive the direction of research and development. https://dfrws.org Forensic Science International: Digital Investigation 33 (2020) 301012 Contents lists available at ScienceDirect Forensic Science International: Digital Investigation journal homepage: www.elsevier.com/locate/fsidi DFRWS 2020 USA d Proceedings of the Twentieth Annual DFRWS USA Hiding Process Memory Via Anti-Forensic Techniques Ralph Palutke a, **, 1, Frank Block a, b, *, 1, Patrick Reichenberger a, Dominik Stripeika a a Friedrich-Alexander Universitat€ Erlangen-Nürnberg (FAU), Germany b ERNW Research GmbH, Heidelberg, Germany article info abstract Article history: Nowadays, security practitioners typically use memory acquisition or live forensics to detect and analyze sophisticated malware samples. Subsequently, malware authors began to incorporate anti-forensic techniques that subvert the analysis process by hiding malicious memory areas. Those techniques Keywords: typically modify characteristics, such as access permissions, or place malicious data near legitimate one, Memory subversion in order to prevent the memory from being identified by analysis tools while still remaining accessible. -
Linux on IBM Z
Linux on IBM Z Pervasive Encryption with Linux on IBM Z: from a performance perspective Danijel Soldo Software Performance Analyst Linux on IBM Z Performance Evaluation _ [email protected] IBM Z / Danijel Soldo – Pervasive Encryption with Linux on IBM Z: from a performance perspective / © 2018 IBM Corporation Notices and disclaimers • © 2018 International Business Machines Corporation. No part of • Performance data contained herein was generally obtained in a this document may be reproduced or transmitted in any form controlled, isolated environments. Customer examples are without written permission from IBM. presented as illustrations of how those • U.S. Government Users Restricted Rights — use, duplication • customers have used IBM products and the results they may have or disclosure restricted by GSA ADP Schedule Contract with achieved. Actual performance, cost, savings or other results in IBM. other operating environments may vary. • Information in these presentations (including information relating • References in this document to IBM products, programs, or to products that have not yet been announced by IBM) has been services does not imply that IBM intends to make such products, reviewed for accuracy as of the date of initial publication programs or services available in all countries in which and could include unintentional technical or typographical IBM operates or does business. errors. IBM shall have no responsibility to update this information. This document is distributed “as is” without any warranty, • Workshops, sessions and associated materials may have been either express or implied. In no event, shall IBM be liable for prepared by independent session speakers, and do not necessarily any damage arising from the use of this information, reflect the views of IBM. -
Linux Performance Tools
Linux Performance Tools Brendan Gregg Senior Performance Architect Performance Engineering Team [email protected] @brendangregg This Tutorial • A tour of many Linux performance tools – To show you what can be done – With guidance for how to do it • This includes objectives, discussion, live demos – See the video of this tutorial Observability Benchmarking Tuning Stac Tuning • Massive AWS EC2 Linux cloud – 10s of thousands of cloud instances • FreeBSD for content delivery – ~33% of US Internet traffic at night • Over 50M subscribers – Recently launched in ANZ • Use Linux server tools as needed – After cloud monitoring (Atlas, etc.) and instance monitoring (Vector) tools Agenda • Methodologies • Tools • Tool Types: – Observability – Benchmarking – Tuning – Static • Profiling • Tracing Methodologies Methodologies • Objectives: – Recognize the Streetlight Anti-Method – Perform the Workload Characterization Method – Perform the USE Method – Learn how to start with the questions, before using tools – Be aware of other methodologies My system is slow… DEMO & DISCUSSION Methodologies • There are dozens of performance tools for Linux – Packages: sysstat, procps, coreutils, … – Commercial products • Methodologies can provide guidance for choosing and using tools effectively • A starting point, a process, and an ending point An#-Methodologies • The lack of a deliberate methodology… Street Light An<-Method 1. Pick observability tools that are: – Familiar – Found on the Internet – Found at random 2. Run tools 3. Look for obvious issues Drunk Man An<-Method • Tune things at random until the problem goes away Blame Someone Else An<-Method 1. Find a system or environment component you are not responsible for 2. Hypothesize that the issue is with that component 3. Redirect the issue to the responsible team 4. -
Technical Support Services for Linux from IBM Robust Linux Support Solutions from an Industry Leader
IBM Technical Support Services Technical Support Services for Linux from IBM Robust Linux support solutions from an industry leader IBM Technical Support Services (TSS) — Highlights Linux Support Summary • IBM’s Operational Support Services — Support Line for Linux is IBM Technical Support Services offers comprehensive, flexible support for Linux a remotely delivered support service designed to answer how-to and environments across all IBM hardware diagnostic questions. Services include: platforms as well as OEM Intel. – Assistance for Linux installation, configuration, usage, Business Impact technical questions, and code-related defects • Helps maximize the return on your Linux – Standard problem determination/resolution investment through increased reliability – Defect support and change team for emergency fixes • Designed to increase IT staff productivity with installation, configuration and – Call-back response from technicians in specialist area within how-to support 2 hours prime shift and 4 hours off shift • Leverage IBM skills and infrastructure to help – Per environment support based on total server count lower your overall Linux operational costs – Support for all IBM hardware platforms and OEM Intel IBM Value – Red Hat or SUSE Linux, IBM Director, VMware and US • Unmatched breadth, depth, reach Citizens support available • Unparalleled speed to resolution – Linux subscription options available • Access to relevant OEM vendors and IBM Linux Technology Center • Enhanced Services (i.e. Account Advocate, Enhanced Technical Support, -
Improving the Performance of Hybrid Main Memory Through System Aware Management of Heterogeneous Resources
IMPROVING THE PERFORMANCE OF HYBRID MAIN MEMORY THROUGH SYSTEM AWARE MANAGEMENT OF HETEROGENEOUS RESOURCES by Juyoung Jung B.S. in Information Engineering, Korea University, 2000 Master in Computer Science, University of Pittsburgh, 2013 Submitted to the Graduate Faculty of the Kenneth P. Dietrich School of Arts and Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computer Science University of Pittsburgh 2016 UNIVERSITY OF PITTSBURGH KENNETH P. DIETRICH SCHOOL OF ARTS AND SCIENCES This dissertation was presented by Juyoung Jung It was defended on December 7, 2016 and approved by Rami Melhem, Ph.D., Professor at Department of Computer Science Bruce Childers, Ph.D., Professor at Department of Computer Science Daniel Mosse, Ph.D., Professor at Department of Computer Science Jun Yang, Ph.D., Associate Professor at Electrical and Computer Engineering Dissertation Director: Rami Melhem, Ph.D., Professor at Department of Computer Science ii IMPROVING THE PERFORMANCE OF HYBRID MAIN MEMORY THROUGH SYSTEM AWARE MANAGEMENT OF HETEROGENEOUS RESOURCES Juyoung Jung, PhD University of Pittsburgh, 2016 Modern computer systems feature memory hierarchies which typically include DRAM as the main memory and HDD as the secondary storage. DRAM and HDD have been extensively used for the past several decades because of their high performance and low cost per bit at their level of hierarchy. Unfortunately, DRAM is facing serious scaling and power consumption problems, while HDD has suffered from stagnant performance improvement and poor energy efficiency. After all, computer system architects have an implicit consensus that there is no hope to improve future system’s performance and power consumption unless something fundamentally changes. -
On Access Control Model of Linux Native Performance Monitoring Motivation
On access control model of Linux native performance monitoring Motivation • socialize Perf access control management to broader community • promote the management to security sensitive production environments • discover demand on extensions to the existing Perf access control model 2 Model overview • Subjects: processes • Access control: • superuser root • LSM hooks for MAC (e.g. SELinux) subjects • privileged user groups • Linux capabilities (DAC) • unprivileged users • perf_event_paranoid sysctl access and • Objects: telemetry data • Resource control: • tracepoints, OS events resource control • CPU time: sample rate & throttling • CPU • Memory: perf_events_mlock_kb sysctl • Uncore Objects • Other HW • File descriptors: ulimit -n (RLIMIT_NOFILE) system • Scope • Level user cgroups • process • user mode • cgroups • kernel kernel • system process • hypervisor hypervisor 3 Subjects Users • root, superuser: • euid = 0 and/or CAP_SYS_ADMIN • unprivileged users: • perf_event_paranoid sysctl • Perf privileged user group: -rwxr-x--- 2 root perf_users 11M Oct 19 15:12 perf # getcap perf perf = cap_perfmon,…=ep root unprivileged Perf users 4 Telemetry, scope, level Telemetr Objects: SW, HW telemetry data y Uncore • tracepoints, OS events, eBPF • CPUs events and related HW CPU • Uncore events (LLC, Interconnect, DRAM) SW events • Other (e.g. FPGA) process cgroup user Scope: Level: system kernel • process • user hypervisor • cgroups • kernel Scope Leve • system wide • hypervisor l 5 perf: interrupt took too long (3000 > 2000), lowering kernel.perf_event_max_sample_rate -
Review Der Linux Kernel Sourcen Von 4.9 Auf 4.10
Review der Linux Kernel Sourcen von 4.9 auf 4.10 Reviewed by: Tested by: stecan stecan Period of Review: Period of Test: From: Thursday, 11 January 2018 07:26:18 o'clock +01: From: Thursday, 11 January 2018 07:26:18 o'clock +01: To: Thursday, 11 January 2018 07:44:27 o'clock +01: To: Thursday, 11 January 2018 07:44:27 o'clock +01: Report automatically generated with: LxrDifferenceTable, V0.9.2.548 Provided by: Certified by: Approved by: Account: stecan Name / Department: Date: Friday, 4 May 2018 13:43:07 o'clock CEST Signature: Review_4.10_0_to_1000.pdf Page 1 of 793 May 04, 2018 Review der Linux Kernel Sourcen von 4.9 auf 4.10 Line Link NR. Descriptions 1 .mailmap#0140 Repo: 9ebf73b275f0 Stephen Tue Jan 10 16:57:57 2017 -0800 Description: mailmap: add codeaurora.org names for nameless email commits ----------- Some codeaurora.org emails have crept in but the names don't exist for them. Add the names for the emails so git can match everyone up. Link: http://lkml.kernel.org/r/[email protected] 2 .mailmap#0154 3 .mailmap#0160 4 CREDITS#2481 Repo: 0c59d28121b9 Arnaldo Mon Feb 13 14:15:44 2017 -0300 Description: MAINTAINERS: Remove old e-mail address ----------- The ghostprotocols.net domain is not working, remove it from CREDITS and MAINTAINERS, and change the status to "Odd fixes", and since I haven't been maintaining those, remove my address from there. CREDITS: Remove outdated address information ----------- This address hasn't been accurate for several years now. -
Kernel Runtime Security Instrumentation Process Is Executed
Kernel Runtime Security Instrumentation KP Singh Linux Plumbers Conference Motivation Security Signals Mitigation Audit SELinux, Apparmor (LSMs) Perf seccomp Correlation with It's bad, stop it! maliciousness but do not imply it Adding a new Signal Signals Mitigation Update Audit Audit (user/kernel) SELinux, Apparmor (LSMs) to log environment Perf variables seccomp Security Signals Mitigation Audit SELinux, Apparmor (LSMs) Perf seccomp Update the mitigation logic for a malicious actor with a known LD_PRELOAD signature Signals ● A process that executes and deletes its own executable. ● A Kernel module that loads and "hides" itself ● "Suspicious" environment variables. Mitigations ● Prevent mounting of USB drives on servers. ● Dynamic whitelist of known Kernel modules. ● Prevent known vulnerable binaries from running. How does it work? Why LSM? ● Mapping to security behaviours rather than the API. ● Easy to miss if instrumenting using syscalls (eg. execve, execveat) ● Benefit the LSM ecosystem by incorporating feedback from the security community. Run my code when a Kernel Runtime Security Instrumentation process is executed /sys/kernel/security/krsi/process_execution my_bpf_prog.o (bprm_check_security) bpf [BPF_PROG_LOAD] open [O_RDWR] securityfs_fd prog_fd bpf [BPF_PROG_ATTACH] LSM:bprm_check_security (when a process is executed) KRSI's Hook Other LSM Hooks Tying it all Together Reads events from the buffer and processes them Userspace further Daemon/Agent User Space Buffer Kernel Space eBPF programs output to a buffer process_execution -
Thread Scheduling in Multi-Core Operating Systems Redha Gouicem
Thread Scheduling in Multi-core Operating Systems Redha Gouicem To cite this version: Redha Gouicem. Thread Scheduling in Multi-core Operating Systems. Computer Science [cs]. Sor- bonne Université, 2020. English. tel-02977242 HAL Id: tel-02977242 https://hal.archives-ouvertes.fr/tel-02977242 Submitted on 24 Oct 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Ph.D thesis in Computer Science Thread Scheduling in Multi-core Operating Systems How to Understand, Improve and Fix your Scheduler Redha GOUICEM Sorbonne Université Laboratoire d’Informatique de Paris 6 Inria Whisper Team PH.D.DEFENSE: 23 October 2020, Paris, France JURYMEMBERS: Mr. Pascal Felber, Full Professor, Université de Neuchâtel Reviewer Mr. Vivien Quéma, Full Professor, Grenoble INP (ENSIMAG) Reviewer Mr. Rachid Guerraoui, Full Professor, École Polytechnique Fédérale de Lausanne Examiner Ms. Karine Heydemann, Associate Professor, Sorbonne Université Examiner Mr. Etienne Rivière, Full Professor, University of Louvain Examiner Mr. Gilles Muller, Senior Research Scientist, Inria Advisor Mr. Julien Sopena, Associate Professor, Sorbonne Université Advisor ABSTRACT In this thesis, we address the problem of schedulers for multi-core architectures from several perspectives: design (simplicity and correct- ness), performance improvement and the development of application- specific schedulers.