From: Andy Lutomirski <luto@amacapital.net>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Jan Beulich <jbeulich@suse.com>, Ingo Molnar <mingo@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Sebastian Lackner <sebastian@fds-team.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Chuck Ebbert <cebbert.lkml@gmail.com>,
Anish Bhatt <anish@chelsio.com>,
Thomas Gleixner <tglx@linutronix.de>,
"linux-tip-commits@vger.kernel.org"
<linux-tip-commits@vger.kernel.org>
Subject: Re: [tip:x86/asm] sched/x86_64: Don't save flags on context switch
Date: Mon, 3 Nov 2014 14:37:07 -0800 [thread overview]
Message-ID: <CALCETrUMLaz_McO=f-v6JmPY7pJSU4M4g1+p1un1UiVcNf+4XQ@mail.gmail.com> (raw)
In-Reply-To: <20141103215837.GB8711@redhat.com>
On Mon, Nov 3, 2014 at 1:58 PM, Oleg Nesterov <oleg@redhat.com> wrote:
> On 11/03, Oleg Nesterov wrote:
>>
>> On 11/03, Andy Lutomirski wrote:
>> >
>> > And do we ever have TF set during a context switch? I hope not.
>>
>> I too hope.
>>
>> > Also, what's with 'jmp exit_intr' at the end of retint_kernel? Why
>> > isn't that 'jmp retint_kernel'?
>>
>> Even better, why not "jmp retint_restore_args" ?
>>
>> preempt_schedule_irq() checks need_resched() and returns with irqs
>> disabled, not need to to recheck test_preempt_need_resched() ?
Seems reasonable to me. Want to write the patch?
>
> Btw, why retint_kernel() checks "interrupts on" ? It seems to me that
> that "interrupts off" is not possible, no? And this will be more clear
> when we remove the "exit_intr" label.
We might get there from #MC or from any of a number of synchronous
errors (#GP from xyz_safe, #PF from some atomic uaccess thing or a
vmap fault, etc), and all of those have interrupts off.
--Andy
>
> Oleg.
>
--
Andy Lutomirski
AMA Capital Management, LLC
next prev parent reply other threads:[~2014-11-03 22:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-01 18:28 [PATCH v3 0/2] x86_64,entry: Clear NT on entry and speed up switch_to Andy Lutomirski
2014-10-01 18:28 ` [PATCH v3 1/2] x86_64,entry: Filter RFLAGS.NT on entry from userspace Andy Lutomirski
2014-10-01 18:28 ` [PATCH v3 2/2] x86_64: Don't save flags on context switch Andy Lutomirski
2014-10-01 18:35 ` H. Peter Anvin
2014-10-01 18:44 ` Andy Lutomirski
2014-10-20 18:52 ` Andy Lutomirski
2014-10-28 11:14 ` [tip:x86/asm] sched/x86_64: " tip-bot for Andy Lutomirski
2014-11-03 21:11 ` Andy Lutomirski
2014-11-03 21:47 ` Oleg Nesterov
2014-11-03 21:58 ` Oleg Nesterov
2014-11-03 22:37 ` Andy Lutomirski [this message]
2014-11-03 22:57 ` Oleg Nesterov
2014-11-03 23:02 ` Andy Lutomirski
2014-11-03 23:10 ` Oleg Nesterov
2014-11-04 23:09 ` Oleg Nesterov
2014-11-03 22:17 ` H. Peter Anvin
2014-10-01 18:34 ` [PATCH v3 0/2] x86_64,entry: Clear NT on entry and speed up switch_to H. Peter Anvin
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