[EN] SSD - which scheduler?

[sunrat]

I was just reading Debian wiki article on SSD optimisation. It recommends setting the I/O scheduler to deadline. Mine is (default from installation of December):

Code: [Select]

/sys/block/sda/queue/scheduler is noop deadline [cfq]Is there any advantage/disadvantage to using deadline instead of cfq?

Also in that article is a link to http://siduction.org/index.php?module=news&func=display&sid=78 which just lands on the forum main page. Is this post still around somewhere? Is there a siduction SSD guide anywhere? I couldn't see one with a quick search of manual and wiki.
Found it.
http://news.siduction.org/2012/01/ssd-partitioning-partition-alignment-optimal-configuration-settings-and-performance-testing/
 Some advice is now redundant, such as Alignment which I believe is usually automatic in current partition tools.
The Debian wiki page seems like a good up-to-date guide - https://wiki.debian.org/SSDOptimization

[dibl]

That article is showing its age -- it is only 2 years old but so many obsolete items!   


- The experiment with power saving in pm-utils is over and control of the journal commit frequency is reverted back to a mount option -- I use "commit=120".


- /run/shm is no longer.  Today you can use /run/user/nnnn for the browser cache, where "nnnn" is the user number.




AFAIK, the deadline scheduler remains the most efficient choice for a SSD, for typical use cases.

[sunrat]

I've just done a bit more searching on this. Consensus seems to be that cfq and deadline both offer similar performance, but one may suit particular use cases better than the other where latency or throughput matter.

Some good info here -

Solid State Drives - ArchWiki - https://wiki.archlinux.org/index.php/Solid_State_Drives

SSD Misconceptions on Linux - Alignment, IO Scheduler, TRIM - https://communities.intel.com/community/itpeernetwork/blog/2013/12/11/ssd-misconceptions-on-linux--alignment-io-scheduler-trim

[KidIcarus]

There is a benchmark comparing all 3 scheduling algorithms:


http://www.phoronix.com/scan.php?page=article&item=linux_iosched_2012&num=1


Depending on your setup (SSD/HDD) and your main taskload it can be positive to switch to a differen scheduler. If there are really noticeable real-world implications I do not know.