Describes how Clear Linux OS is designed, highlighting core features, operating models, and foundational tools that are key to understanding how the distro operates.

1. Clear Linux* OS
Architecture Overview
Patrick McCarty - Software Engineer
*Other names and brands may be claimed as the property of others

2. © 2018 Intel Corporation. Intel, the Intel logo, Intel Inside, the Intel Inside logo, Intel Experience What’s Inside, The Intel Experience What’s Inside logo, and Xeon are trademarks of Intel Corporation in the U.S.
and/or other countries. *Other names and brands may be claimed as the property of others.
Intel technologies’ features and benefits depend on system configuration and may require enabled hardware, software or service activation. Learn more at intel.com, or from the OEM or retailer.
Intel processors of the same SKU may vary in frequency or power as a result of natural variability in the production process.
For more complete information about performance and benchmark results, visit www.intel.com/benchmarks.
The cost reduction scenarios described are intended to enable you to get a better understanding of how the purchase of a given Intel based product, combined with a number of situation-specific variables, might
affect future costs and savings. Circumstances will vary and there may be unaccounted-for costs related to the use and deployment of a given product. Nothing in this document should be interpreted as either a
promise of or contract for a given level of costs or cost reduction.
Intel does not control or audit third-party benchmark data or the web sites referenced in this document. You should visit the referenced web site and confirm whether referenced data are accurate.
Optimization Notice: Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2,
SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-
dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the
applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice. Notice Revision #20110804.
No computer system can be absolutely secure.
Intel® Advanced Vector Extensions (Intel® AVX)* provides higher throughput to certain processor operations. Due to varying processor power characteristics, utilizing AVX instructions may cause a) some parts to
operate at less than the rated frequency and b) some parts with Intel® Turbo Boost Technology 2.0 to not achieve any or maximum turbo frequencies. Performance varies depending on hardware, software, and
system configuration and you can learn more at http://www.intel.com/go/turbo.
Available on select Intel® processors. Requires an Intel® HT Technology-enabled system. Your performance varies depending on the specific hardware and software you use. Learn more by visiting
http://www.intel.com/info/hyperthreading.
§ Configurations: The testing was done on Based on fourth-generation Intel Xeon E5-2699 v4 @2.20 GHz processor with 22 cores, 55 MB LLC and 62 GB memory 16 1G hugepages. The testing was conducted in OPNFV
Pharos testbed on Pod 12 by VSPERF community engineers
Intel, the Intel logo are trademarks of Intel Corporation or its subsidiaries in the U.S. and/or other countries.
*Other names and brands may be claimed as the property of others.
© Intel Corporation
Legal Disclaimer

3. Agenda
● Clear Linux* OS Overview
● Performance optimizations
● Use-case focused bundles
● Stateless OS design
● Telemetry
● Updates
*Other names and brands may be claimed as the property of others

4. Clear Linux* OS Overview
● Optimized for IA
● Rolling release distribution
● Average of 9 releases per week
● Developer-focused
*Other names and brands may be claimed as the property of others

5. Performance Optimizations
● Optimize the entire stack
● Compiler flags
○ Westmere baseline
○ Haswell tuned
● Optimized libraries selected at runtime based
on available CPU features
● Performance patches to packages
● Example optimized package:
https://github.com/clearlinux-
pkgs/opencv/blob/master/opencv.spec
Program using OpenCV*
AVX2-enabled CPU
dynamic linker
libopencv_*.so (base)
libopencv_*.so (avx2)
*Other names and brands may be claimed as the property of others

6. Use-Case Focused Bundles
● Bundles provide use-case driven
functionality to end user
● Dependencies resolved at build time on
server, not at install or runtime
● Similar to package groups in other distros
● Vertically vs horizontally integrated os-core
os-core-update
network-basic
webserver openssl
python-basic
application-server
kvm-host
ansible iproute2
virt-manager
scm-server
cloud-control
*Other names and brands may be claimed as the property of others

7. TRADITIONAL OS
User Data
System Configuration
Operating System
CLEAR LINUX* OS
User Data
System Configuration
Operating System
Stateless
● OS provides functional and secure default
configuration in /usr
● Defaults can be overridden or modified in /etc
and the home directory
● Wiping /etc and /var performs a "factory reset",
restoring OS default configs
*Other names and brands may be claimed as the property of others

8. Stateless – example
● Default telemetrics.conf from operating system in /usr
record_expiry=1200
spool_max_size=5120
spool_process_time=900
rate_limit_enabled=true
record_burst_limit=1000
record_window_length=15

9. Stateless – example
● Default telemetrics.conf from operating system in /usr
● Custom configuration in /etc
record_expiry=1200
spool_max_size=5120
spool_process_time=900
rate_limit_enabled=true
record_burst_limit=1000
record_window_length=15
record_expiry=1200
spool_max_size=5120
spool_process_time=900
rate_limit_enabled=false
record_burst_limit=1000
record_window_length=15

10. Stateless – example
● Default telemetrics.conf from operating system in /usr
● Custom configuration in /etc
record_expiry=1200
spool_max_size=5120
spool_process_time=900
rate_limit_enabled=true
record_burst_limit=1000
record_window_length=15
record_expiry=1200
spool_max_size=5120
spool_process_time=900
rate_limit_enabled=false
record_burst_limit=1000
record_window_length=15

11. Telemetry
● Opt-in telemetry solution
● Lightweight client service
● Client-side probes send records to help debug software anomalies.
● Probes avoid collecting personally identifiable information and records
comply with Privacy Policy*.
● Records are analyzed and displayed in a developer-oriented format on the
telemetry server.
* https://www.intel.com/content/www/us/en/privacy/intel-privacy-notice.html

12. Probe
Probe
Probe
…
telemprobd
libtelemetry
telempostd
Server
Telemetry – Client architecture

13. Updating
● All installed bundles are updated at once
○ Entire system update (one OS version)
○ QA is done on the entire OS release at once
● Proportional updates
● Auto-update on by default

14. Update content created by mixer tool
Upstream
Sources
Bundle
definitions
Bundle A
data
Bundle B
data
Bundle C
data
Full chroot
Update Creator
Update
Creator
Update
Artifacts
Swupd
clients...
swupd
clients...
Mixing

15. Mixing – Update artifacts
Manifests
MANIFEST 24 # OS tooling/content format
version: 21260 # OS Version this manifest describes
previous: 21220 # Previous change to this manifest at this OS version
filecount: 13624 # Number of files in the manifest
timestamp: 1520706949 # Epoch of creation
contentsize: 811403622 # Size, in bytes, of this bundle (not accounting for included bundles)
includes: os-core # Bundle included by this bundle
F... 0437fc1556fdfe08ee8cfa492094e5c11a86b7b793213767d4f5697d9b437b36 21080 /usr/bin/c_hash
F... 4fdebd92c2ad33ad063c8de973b4eafa35d800ff70abe75644172ae6d0b81436 21080 /usr/bin/corelist
< 13622 more entries >
Manifest of Manifests (MoM)
M... 39be958b03625d0507222996f167de279bc2edaec9a1ff45a86f3cdfac83ca6a 21080 desktop-autostart
M... 3ac656e9bdb43871f5345cf71c866a67a58d3ce0a2a085efb8e703be4dd3d753 21080 desktop-locales
M... 1dbd2354eb2cbf47a871a4d70fc5cee0dc0e6df2c940b03ab6d5ac2edbad594d 21080 dhcp-server

16. Manifest.MoM signed, verification cascades through SHA256 hashes
hashes verifiedhashes verified
Manifest.MoM
Manifest.MoM.sig
Manifest.os-core
Manifest.go-basic
Manifest.shells
Manifest.editors
Manifest.desktop
...
/usr
/usr/bin/bash
/usr/bin/cat
/usr/bin/chmod
/usr/bin/rm
...
/usr/bin/chown
/usr/bin/chroot
Mixing – Security

17. Mixing – Update artifacts
● Packs
○ Delta-packs (from version x to y, content difference between versions)
Binary deltas
○ Zero-packs (from version 0, complete content of bundle)
● Full files (for fallback)
○ Compressed full files available for download if pack download/extraction fails

18. NON-ATOMIC
ms-s durationATOMIC
Download +
verify MoM
Download +
extract packs
Apply delta
files and stage
Verify pack
contents with
manifests
Rename
staged to final
Update
Artifacts
Updating – Client Operation

19. Clear Linux
bundles and
content
Mixer Update
Artifacts
swupd
clients...
User bundles and
content
Creating Custom Mixes
Useful for teams that want to provide their own content on top of Clear
Linux* OS content for development, testing, etc.
*Other names and brands may be claimed as the property of others

20. mixin
Useful for individual users that want
to add their own content
User adds
package Mixer Local
Artifacts
Upstream
Artifacts
Merge
swupd
client
Side-loading Custom Content

21. Clear Linux* OS
● Rolling release security updates
● Stateless OS design
● Performance focused
● Use-case optimized bundles
● Fast, secure, and reliable updates
*Other names and brands may be claimed as the property of others

22. Contact details
Patrick McCarty
pmccarty on #clearlinux (freenode)
More resources:
Project site: clearlinux.org
Forum: community.clearlinux.org
Git repos:
github.com/clearlinux
github.com/clearlinux-pkgs