linux-kernel - Re: Real-time scheduling policies and hyper-threading

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 24 Apr 2014 22:24:43 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Kirill Tkhai <tkhai@...dex.ru>
Cc:	Roman Gushchin <klamm@...dex-team.ru>,
	LKML <linux-kernel@...r.kernel.org>,
	"mingo@...hat.com" <mingo@...hat.com>,
	Artyom Tarasenko <atar4qemu@...il.com>
Subject: Re: Real-time scheduling policies and hyper-threading

On Fri, Apr 25, 2014 at 12:16:52AM +0400, Kirill Tkhai wrote:
> 24.04.2014, 22:59, "Peter Zijlstra" <peterz@...radead.org>:
> 
> [snip]
> 
> >>  Does anyone use rt-scheduler for runtime-like cpu-bound tasks?
> >
> > So in general cpu bound tasks in the RT classes (FIFO/RR/DEADLINE) are
> > bad and can make the system go funny.
> >
> > For general system health it is important that various system tasks
> > (kthreads usually) can run. Many of these kthreads run at !rt prios, and
> > by having cpu bound tasks in rt prios they don't get to run.
> 
> One more word to this. I had such expirience on 2.6.33 kernel with RT patch
> and weak hardware (sparc32).
> 
> Networking was actively used and application did not use any IO operations.
> 
> User needs to set all RT priorities by himself. It's necessary to set RT
> priorities at least for softirqs and rcus. RT bandwidth must be switched
> off.
> 
> The most giving optimization, which I receive, was after rejection from NAPI
> for network adapters and splitting interrupt handler on hard and threadparts.
> In this case game with binding for everything strongly improves the picture
> for single problem.

Sure, it can be made to work, but you really need to know what you're
doing and you get to keep all pieces when it comes apart :-)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/