1. Computers
  2. Display Drivers
  3. Graphics Cards
  4. Memory
  5. Motherboards
  6. Processors
  7. Software
  8. Storage
  9. Operating Systems


Facebook RSS Twitter Twitter Google Plus


Phoronix Test Suite

OpenBenchmarking Benchmarking Platform
Phoromatic Test Orchestration

Google Wants Fast Queue Spinlocks For The Linux Kernel

Linux Kernel

Published on 23 January 2013 02:03 AM EST
Written by Michael Larabel in Linux Kernel
1 Comment

A Google engineer has proposed "Fast Queue Spinlocks" for the Linux kernel as an alternative in select cases to the default ticket spinlock.

In terms of "Fast Queue Spinlocks", Michel Lespinasse of Google wrote:
I understand that in the past, such proposals have been defeated by two main arguments:

- That it is generally preferable to use smart algorithms that can avoid lock contention altogether, rather than spending effort on the lock itself to deal with the contention, and
- That the lightly contended case matters more to real workloads than the highly contended case, and that the most well known scalable spinlock algorithms tend to be relatively slow in the lightly contended case.

I am hoping for a different result this time around based on the following counter-arguments:

- There are situations where the lock contention is directly driven by user events, with little opportunity to reduce it in-kernel. One example might be when the user requests that the kernel acquires or releases semaphores on its behalf using sysv IPC APIs - it is hard to imagine how the kernel could mitigate spinlock contention issues for the user.
- More importantly, the queue spinlock implementation I am proposing seems to behave well both under light and heavy contention. It uses one single atomic operation on the lock side, and (on x86) only a single memory store on the unlock side, with fairly short code sections on both sides, and just compares well with the ticket spinlock on the benchmarks I have tried. To be clear, I am not proposing replacing every ticket spinlock usage with queue spinlocks; I am only proposing to have both APIs available and pick them as appropriate for each use case.
For demonstrating his queue spinlock proposal, Lespinasse converted the IPC object spinlock and network qdisc busylock to the new interface. He's published the six patches to the Linux kernel mailing list for comments and suggestions by fellow Linux kernel developers. He has also provided some preliminary benchmarks of Fast Queue Spinlocks.

The patch-set and discussion about Fast Queue Spinlocks for the Linux kernel can be found here.

About The Author
Michael Larabel is the principal author of Phoronix.com and founded the web-site in 2004 with a focus on enriching the Linux hardware experience and being the largest web-site devoted to Linux hardware reviews, particularly for products relevant to Linux gamers and enthusiasts but also commonly reviewing servers/workstations and embedded Linux devices. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics hardware drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated testing software. He can be followed via and or contacted via .
Latest Articles & Reviews
  1. Ubuntu 15.04 Offers Faster OpenGL For AMD Radeon GPUs On Open-Source
  2. Ubuntu 15.04 Brings Some Graphics Performance Improvements For Intel Haswell
  3. Sub-$20 802.11n USB WiFi Adapter That's Linux Friendly
  4. The Lenovo T450s Is Working Beautifully With Linux
  5. Linux 4.0 SSD EXT4 / Btrfs / XFS / F2FS Benchmarks
  6. Linux 4.0 Hard Drive Comparison With Six File-Systems
Latest Linux News
  1. Phoronix Server Migration
  2. GCC 5.2 Will Come In Two To Three Months
  3. AMD FP3 Motherboard Ported To Coreboot
  4. The Difference In Optimizations Between NIR & GLSL
  5. OpenMandriva Lx 3 Alpha: Adds UEFI Support, Defaults To LXQt
  6. Systemd Kills Off Shutdownd
  7. There's Now More Than 1,100 Games On Steam For Linux
  8. Btrfs In Linux 4.1 Has Fixes For File-Systems Of 20 Terabytes & Up
  9. Microsoft's CoreCLR Now Works On FreeBSD
  10. Unigine 2.0 Beta 2 Brings PBR, SSR, Kinect 2 Support
Most Viewed News This Week
  1. AMD Releases New "AMDGPU" Linux Kernel Driver & Mesa Support
  2. Ubuntu's Desktop-Next Switching From .DEBs To Snappy
  3. My Favorite Computer Desk Of The Past Decade For Less Than $100
  4. AMD Open-Sources "Addrlib" From Catalyst
  5. Library Operating System (LibOS) For Linux Still Being Pursued
  6. Debian 8.0 Jessie Is Ready For Release This Weekend
  7. GIMP's Porting To GTK3 Continues
  8. Features Thus Far For The Linux 4.1 Kernel