linux-kernel - Re: [RFC] Thread Migration Preemption

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 for Android: free password hash cracker in your pocket

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

Message-Id: <1183675606.17319.83.camel@localhost.localdomain>
Date:	Thu, 05 Jul 2007 18:46:46 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
Cc:	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [RFC] Thread Migration Preemption

On Thu, 2007-07-05 at 17:51 -0400, Mathieu Desnoyers wrote:
> Thread Migration Preemption
> 
> This patch adds the ability to protect critical sections from migration to
> another CPU without disabling preemption.
> 
> This will be useful to minimize the amount of preemption disabling for the -rt
> patch. It will help leveraging improvements brought by the local_t types in
> asm/local.h (see Documentation/local_ops.txt). Note that the updates done to
> variables protected by migration_disable must be either atomic or protected from
> concurrent updates done by other threads.
> 
> Typical use:
> 
> migration_disable();
> local_inc(&__get_cpu_var(&my_local_t_var));
> migration_enable();
> 
> Which will increment the variable atomically wrt the local CPU.
> 
> Comments (such as how to integrate this in the already almost full
> preempt_count) are welcome.

Ingo and Thomas, this also would help with the IRQ thread running a
softirq issue.  We wouldn't need to bind to a CPU the thread. We could
simply disable the ability to migrate while the IRQ thread was handling
the softirqs.

-- Steve


-
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/