Bug 2314193

Summary:	Non-optimal packaging leads to bad performance
Product:	[Fedora] Fedora	Reporter:	Andreas Rogge <andreas.rogge>
Component:	xxhash	Assignee:	Mattias Ellert <mattias.ellert>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	medium	Docs Contact:
Priority:	unspecified
Version:	rawhide	CC:	mattias.ellert
Target Milestone:	---	Keywords:	Performance, RFE, UserExperience
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:	xxhash-0.8.2-4.fc42 xxhash-0.8.2-4.fc40 xxhash-0.8.2-4.fc41 xxhash-0.8.2-4.fc39	Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2024-10-03 15:50:42 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Andreas Rogge 2024-09-23 11:10:50 UTC

I found two issues here:

1. build flags
xxHash adds -O3 by itself, RPM adds -O2 after that.
This results in binaries that are built with -O2, where -O3 is required for decent performance, which is why xxHash insists on building with -O3 in the first place.

2. DISPATCH=1 set on build, but not in install
xxHash supports dynamic dispatching, i.e. using CPU-level dependant code, on x86_64. While this is enabled in xxhsum and libxxhash, there is no way to consume this feature, as the xxh_x86dispatch.h header is missing from xxhash-devel.
Basically the "make install" also needs DISPATCH=1 to install the header.

Reproducible: Always

Steps to Reproduce:
1. Build a test-program consuming xxhash using the packages library
2. Build the same program using a bundled xxhash
3. Measure runtime of both programs
Actual Results:  
Speed of 1. is two times slower than 2.

Expected Results:  
Speed of the build from 1. should be in the ballpark of 2.

I measured on an Intel i7-7820HQ.
While -O3 doesn't provide huge gains if dispatching is enabled, it is probably worth having for non-x86 platforms.

Comment 1 Andreas Rogge 2024-09-25 16:04:20 UTC

I created a pull-request to package the headerfile.
I currently have no idea how to fix the -O2 vs -O3 issue though.

Comment 2 Fedora Update System 2024-10-03 14:11:06 UTC

FEDORA-2024-3e3e517b53 (xxhash-0.8.2-4.fc42) has been submitted as an update to Fedora 42.
https://bodhi.fedoraproject.org/updates/FEDORA-2024-3e3e517b53

Comment 3 Fedora Update System 2024-10-03 15:42:23 UTC

FEDORA-2024-3d8c04544c (xxhash-0.8.2-4.fc39) has been submitted as an update to Fedora 39.
https://bodhi.fedoraproject.org/updates/FEDORA-2024-3d8c04544c

Comment 4 Fedora Update System 2024-10-03 15:42:23 UTC

FEDORA-2024-e55072091c (xxhash-0.8.2-4.fc41) has been submitted as an update to Fedora 41.
https://bodhi.fedoraproject.org/updates/FEDORA-2024-e55072091c

Comment 5 Fedora Update System 2024-10-03 15:42:25 UTC

FEDORA-2024-3c4e7ae2ea (xxhash-0.8.2-4.fc40) has been submitted as an update to Fedora 40.
https://bodhi.fedoraproject.org/updates/FEDORA-2024-3c4e7ae2ea

Comment 6 Fedora Update System 2024-10-03 15:50:42 UTC

FEDORA-2024-3e3e517b53 (xxhash-0.8.2-4.fc42) has been pushed to the Fedora 42 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 7 Fedora Update System 2024-10-04 01:41:03 UTC

FEDORA-2024-3c4e7ae2ea has been pushed to the Fedora 40 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2024-3c4e7ae2ea`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2024-3c4e7ae2ea

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 8 Fedora Update System 2024-10-04 02:18:35 UTC

FEDORA-2024-3d8c04544c has been pushed to the Fedora 39 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2024-3d8c04544c`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2024-3d8c04544c

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 9 Fedora Update System 2024-10-04 02:57:02 UTC

FEDORA-2024-e55072091c has been pushed to the Fedora 41 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2024-e55072091c`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2024-e55072091c

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 10 Fedora Update System 2024-10-06 02:11:42 UTC

FEDORA-2024-3c4e7ae2ea (xxhash-0.8.2-4.fc40) has been pushed to the Fedora 40 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 11 Fedora Update System 2024-10-08 02:02:30 UTC

FEDORA-2024-e55072091c (xxhash-0.8.2-4.fc41) has been pushed to the Fedora 41 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 12 Fedora Update System 2024-10-19 01:18:56 UTC

FEDORA-2024-3d8c04544c (xxhash-0.8.2-4.fc39) has been pushed to the Fedora 39 stable repository.
If problem still persists, please make note of it in this bug report.