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.org

Multi-Queue Block Layer Is Merged For Linux 3.13

Linux Kernel

Published on 14 November 2013 09:53 AM EST
Written by Michael Larabel in Linux Kernel
2 Comments

The multi-queue block layer (blk-mq) has indeed made it for Linux 3.13 as one (of many other) exciting features. The multi-queue block layer can lead to better SSD performance through reducing latency by balancing I/O workload across multiple CPU cores and allowing for multiple hardware queues.

Since earlier this month we were expecting Linux 3.13 To Receive Multi-Queue Block Layer. The block layer pull request was submitted with this support and it didn't receive any objections from Linus Torvalds or any other kernel developers, so it's now in.

While this is a big win, not all drivers have been converted yet to the new interface but more work will happen for Linux 3.14. More details can be found via the Git pull message for this blk-mq support.
This is a new and more scalable queueing model that marries the best part of the request based interface we currently have (which is fully featured, but scales poorly) and the bio based "interface" which the new drivers for high IOPS devices end up using because it's much faster than the request based one.

The bio interface has no block layer support, since it taps into the stack much earlier. This means that drivers end up having to implement a lot of functionality on their own, like tagging, timeout handling, requeue, etc. The blk-mq interface provides all these. Some drivers even provide a switch to select bio or rq and has code to handle both, since things like merging only works in the rq model and hence is faster for some workloads. This is a huge mess. Conversion of these drivers nets us a substantial code reduction. Initial results on converting SCSI to this model even shows an 8x improvement on single queue devices. So while the model was intended to work on the newer multiqueue devices, it has substantial improvements for "classic" hardware as well. This code has gone through extensive testing and development, it's now ready to go. A pull request is coming to convert virtio-blk to this model will be will be coming as well, with more drivers scheduled for 3.14 conversion.

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 Linux Hardware Reviews
  1. Intel Xeon E5-1680 v3 & E5-2687W v3 Compared To The Core i7 5960X On Linux
  2. Intel 120GB 530 Series SSD Linux Performance
  3. Btrfs/EXT4/XFS/F2FS RAID 0/1/5/6/10 Linux Benchmarks On Four SSDs
  4. AMD's Windows Catalyst Driver Remains Largely Faster Than Linux Drivers
Latest Linux Articles
  1. Mesa 10.5-devel Brings Some Intel Haswell HD Graphics Changes Over Mesa 10.3
  2. NVIDIA vs. Nouveau Drivers With Linux 3.18 + Mesa 10.4-devel
  3. Is The Open-Source NVIDIA Driver Fast Enough For Steam On Linux Gaming?
  4. Linux 3.18 File-System Performance Minimally Changed But Possible Regressions
Latest Linux News
  1. There's New In-Fighting Over The Future Of Compiz
  2. GTK+ Inspector Gains More Features Ahead Of GNOME 3.16
  3. Clang 3.6 Will Hopefully Have OpenMP Support
  4. A Go Front-End Could Soon Be Landing In LLVM
  5. Linux 3.18-rc6 Released, A Worrisome Regression Remains
  6. HandBrake 0.10 Brings H.265 & VP8 Encoders
  7. Gngr: A New Web Browser Focused On Privacy
  8. Linux 3.18 Kernel: Not Much Change With Intel Haswell Performance
  9. More File-System Tests Of The Linux 3.18 Kernel
  10. Using NVIDIA's NVENC On Linux With FFmpeg
Latest Forum Discussions
  1. Roadmap to Catalyst 14.10 ?
  2. how to configure module phoromatic ?
  3. PulseAudio 6.0 Is Coming & Other Linux Audio Plans For The Future
  4. Debian Developer Resigns From The Systemd Maintainership Team
  5. Updated and Optimized Ubuntu Free Graphics Drivers
  6. Cant get working Kaveri APU - A10-7850k
  7. Script for Fan Speed Control
  8. Debian Init System Coupling Vote Results