Scheduler Improvements Published For The Linux 4.6 Kernel

[cj.wijtmans]

Nah, not GPU most likely. GTX780TI, AMD Vishera. Custom compiled kernel + nvidia binary. Need to check if i enabled watchdog, which i think I did not. Cores are never 100%. There are a few programs yet which can take advantage of 8 cores(4FPU cores) at speed of 4GHz.

there is also the wakeup sources garbage collector in the ACPI settings. there are a few other periodic checks that i believe increase latency and you can check.

[dimko]

There are different things to look at regarding performance of games, FPS is a very bad indicator of performance. You can have bad frames and never notice it. What is your bottleneck? if its the gpu than most likely you cant do much regarding performance. Check if all cores are below 100% . When it really comes down to latency disable all periodic things such as garbage collectors and watchdogs that increase latency, it is subtle but you can notice the difference especially when you are on CONFIG_PREEMPT. Because of this update i may give deadline a shot but with two SSDs, a gpu bottleneck and expert kernel tweaks to reduce latency i wont notice any difference i believe.

Nah, not GPU most likely. GTX780TI, AMD Vishera. Custom compiled kernel + nvidia binary. Need to check if i enabled watchdog, which i think I did not. Cores are never 100%. There are a few programs yet which can take advantage of 8 cores(4FPU cores) at speed of 4GHz.

[cj.wijtmans]

I read about it - it's basically auto niceness.
Niceness in vanilla kernel does nothing to make FPS smoother under load.
I manually set all processes to priority 20, then made game -19, no difference whatsoever. So i don't think it will in any way help.

There are different things to look at regarding performance of games, FPS is a very bad indicator of performance. You can have bad frames and never notice it. What is your bottleneck? if its the gpu than most likely you cant do much regarding performance. Check if all cores are below 100% . When it really comes down to latency disable all periodic things such as garbage collectors and watchdogs that increase latency, it is subtle but you can notice the difference especially when you are on CONFIG_PREEMPT. Because of this update i may give deadline a shot but with two SSDs, a gpu bottleneck and expert kernel tweaks to reduce latency i wont notice any difference i believe.

[dimko]

A kernel with CONFIG_SCHED_AUTOGROUP=y shouldn't be that different from a BFS kernel

I read about it - it's basically auto niceness.
Niceness in vanilla kernel does nothing to make FPS smoother under load.
I manually set all processes to priority 20, then made game -19, no difference whatsoever. So i don't think it will in any way help.

[ObiWan]

I wonder, if any of those improvements can make Desktop/gaming experience more fluid?
BFS is nice, but I we need something that is in the kernel...

A kernel with CONFIG_SCHED_AUTOGROUP=y shouldn't be that different from a BFS kernel

[tessio]

Afaik there's a CPU scheduler and a I/O scheduler, your (and mine) issue is with the latter. I'm using BFQ, much better so far than CFQ.

http://lwn.net/Articles/601799/

http://lwn.net/Articles/674308/

Let's hope it get accepted into mainline kernel.

[cl333r]

My Linux Mint 17.3 uses 760MB from the 3072MB available, so memory is not the problem. But every time I'm writing a big file to a disk (internal o external) everything becomes super slow, even the mouse pointer movement start to hang. Is this a scheduler thing? Anyone else experience that? This deadline scheduler could help?


**Edit**
It turns out that I'm already using the deadline scheduler:

$ cat /sys/block/sda/queue/scheduler
noop [deadline] cfq

Afaik there's a CPU scheduler and a I/O scheduler, your (and mine) issue is with the latter. I'm using BFQ, much better so far than CFQ.

http://lwn.net/Articles/601799/

http://lwn.net/Articles/674308/

[c117152]

Oh good some scheduler love. I've also been having system wide freezes with NCQ on over intensive disk I/O where the system becomes unresponsive while long write operations are ongoing.
I always assumes the guy responsible for the scheduling work is some impoverished student working through his dissertation while running a 10 year old 500GB 5600RPM HDD that has slow enough write speeds that he never needs to put in locks

[cynic]

My Linux Mint 17.3 uses 760MB from the 3072MB available, so memory is not the problem. But every time I'm writing a big file to a disk (internal o external) everything becomes super slow, even the mouse pointer movement start to hang. Is this a scheduler thing? Anyone else experience that? This deadline scheduler could help?


**Edit**
It turns out that I'm already using the deadline scheduler:

$ cat /sys/block/sda/queue/scheduler
noop [deadline] cfq

I'd suggest you to take a look at this (if you already didn't)

http://algo.ing.unimo.it/people/paolo/disk_sched/description.php

some says that for some workloads they get worse performance, but surely from the user standpoint the system feels much more fluid even under heavy disk I/O.

[dimko]

My Linux Mint 17.3 uses 760MB from the 3072MB available, so memory is not the problem. But every time I'm writing a big file to a disk (internal o external) everything becomes super slow, even the mouse pointer movement start to hang. Is this a scheduler thing? Anyone else experience that? This deadline scheduler could help?


**Edit**
It turns out that I'm already using the deadline scheduler:

$ cat /sys/block/sda/queue/scheduler
noop [deadline] cfq

There is also I/O scheduler, which is not related to CPU. There is also memory tweak available in the /proc/ file system.
First can prioritize process of writing to HDD/SDD, second can control dirty caching, etc. I am not at home so can't throw in the links. Sound like memory tweaking can do some good to you.
Also, clarify size of file + it's source + where you read it from and where you write it from.

Ideally, open up new thread about it.