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 PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Fri, 11 Apr 2014 20:02:25 -0400 From: Rik van Riel <riel@...hat.com> To: David Miller <davem@...emloft.net> CC: linux-kernel@...r.kernel.org, netdev@...r.kernel.org, jbenc@...hat.com, peterz@...radead.org, tglx@...utronix.de, fweisbec@...il.com Subject: Re: [PATCH] softirq: punt to ksoftirqd if __do_softirq recently looped On 04/11/2014 04:33 PM, David Miller wrote: > From: Rik van Riel <riel@...hat.com> > Date: Thu, 10 Apr 2014 11:57:06 -0400 > >> @@ -330,7 +334,11 @@ void irq_enter(void) >> >> static inline void invoke_softirq(void) >> { >> - if (!force_irqthreads) { >> + /* >> + * If force_irqthreads is set, or if we looped in __do_softirq this >> + * jiffie, punt to ksoftirqd to prevent userland starvation. >> + */ >> + if (!force_irqthreads && this_cpu_read(softirq_looped) != jiffies) { > > If we do this, which I'm not convinced of yet, I think we should use two > jiffies as the cutoff. I am not fully convinced, either. This patch mostly just illustrates the problem, and gives something that solves Jiri's immediate problem. It is quite likely that there is a better way to solve the problem of: 1) softirq handling starving out userspace processing, 2) which could be solved by moving the userspace process elsewhere, and 3) shifting softirq processing to ksoftirqd A working patch seems to be one of the better ways to start a discussion, though. If anybody has a nicer idea on how to solve the problem, I'd even be willing to implement your idea, and give Jiri another patch to test :) -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists