low latency tuning of RHEL 7 - main things to do?

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I'm using my server for HFT trading. I'm using HP guide for tuning http://h10032.www1.hp.com/ctg/Manual/c01804533.pdf
Unfortunately this guide still not updated for RHEL 7, but I've tried to follow it (hoping that things not changed).

Guide suggests:
"Edit /boot/grub/grub.conf and add "nosoftlockup intel_idle.max_cstate=0 mce=ignore_ce" to the kernel line"
In RHEL 7 i have "/boot/grub2/grub.cfg", but it starts with "DO NOT EDIT THIS FILE". So to achive the same effect on RHEL 7 what should I do? Or I should ignore ""DO NOT EDIT THIS FILE" warning?

Where and how should I set this? "Edit /boot/grub/grub.conf and add "idle=poll" to the kernel line". Or, again, I should ignore ""DO NOT EDIT THIS FILE" warning?

(Probably you can suggest something else for low-latency. So far I executed "tuned-adm select network-latency" - this helped a lot. Also I stopped many services and followed Solarflare guide.)

ov
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SW Red Hat Guru 4022 points
8 November 2014 2:08 PM

Hello

Regarding which grub file to edit, see Working with the GRUB 2 Boot Loader

I am sorry I cannot answer about the specific options you mention, but you might like to read this
Performance Tuning Guide guide none the less.

james.radtke@siriusxm.com's picture Guru 6863 points
8 November 2014 3:42 PM

I'll second Stephen's recommendation regarding the grub modifications. I, personally, found grub2 frustrating at first - but, now I'm a fan ;-)

I believe you will want to add your options to the line in /etc/sysconfig/grub

GRUB_CMDLINE_LINUX="..."

Then run

grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg

Which you can validate with

[root@cent7a ~]# grep GRUB_CMDLINE /etc/sysconfig/grub 
GRUB_CMDLINE_LINUX="rd.lvm.lv=vg_cent/lv_swap vconsole.font=latarcyrheb-sun16 crashkernel=auto  vconsole.keymap=us rd.lvm.lv=vg_cent/lv_root rhgb quiet"
[root@cent7a ~]# cat /proc/cmdline 
BOOT_IMAGE=/vmlinuz-3.10.0-123.9.2.el7.x86_64 root=/dev/mapper/vg_cent-lv_root ro rd.lvm.lv=vg_cent/lv_swap vconsole.font=latarcyrheb-sun16 crashkernel=auto vconsole.keymap=us rd.lvm.lv=vg_cent/lv_root rhgb quiet LANG=en_US.UTF-8

As for your tuning, I won't be much help. I think it really depends on the type of low-latency you're after (cluster-internconnect, cache-fusion, HPC, etc...) and regardless I don't have much experience there. If you have a support contract, I would recommend requesting some guidance - and also, as you are creating your case, the portal will make recommendations based on your case that can immediately guide you.

Jeremy Eder's picture Red Hat Pro 788 points
21 January 2015 12:16 PM

https://access.redhat.com/articles/1323793

ov Active Contributor 244 points
2 March 2015 5:28 PM

thanks!

SW Red Hat Guru 4022 points
26 March 2015 7:55 PM

Hello, see also: Red Hat Enterprise Linux Network Performance Tuning Guide on the Red Hat Customer Portal.

os-unix's picture Active Contributor 146 points
26 March 2015 9:44 PM

Hi James,

I do not use EFI on my laptop, but is the grub config in a fedora subdirectory or did you by accident give the instruction for a Fedora installation?

I do not have access to a RHEL 7 server on a physical machine, so I cannot check myself.

Kind regards,

Jan Gerrit

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