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
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Wed, 8 Oct 2014 10:00:16 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/1] sched: fix the PREEMPT_ACTIVE check in
 __trace_sched_switch_state()

On Tue, Oct 07, 2014 at 09:50:46PM +0200, Oleg Nesterov wrote:
> And note that another caller of task_preempt_count(), set_cpu(), is
> fine but it doesn't really need this helper.
> 
> And afaics we do not need ->saved_preempt_count at all, the trivial
> patch below makes it unnecessary, we can kill it and all its users.
> 
> Not only this will simplify the code, this will make (well, almost)
> the per-cpu preempt counter arch-agnostic.
> 
> Or I missed something?

Two things, per-cpu isn't always faster on some archs, and load-store
archs have problems with PREEMPT_NEED_RESCHED, although arguably you can
do per-cpu preempt count without that.

> Do you think this makes sense? If yes, I'll try to make the patches.

It penalizes everything but x86 I think. There is no other arch that has
per-cpu preempt count atm.
--
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/

Powered by blists - more mailing lists