From: Peter Zijlstra <peterz@infradead.org>
To: Rik van Riel <riel@fb.com>
Cc: Song Liu <songliubraving@fb.com>,
"song@kernel.org" <song@kernel.org>,
"joe.lawrence@redhat.com" <joe.lawrence@redhat.com>,
"jpoimboe@redhat.com" <jpoimboe@redhat.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>,
"live-patching@vger.kernel.org" <live-patching@vger.kernel.org>,
"vincent.guittot@linaro.org" <vincent.guittot@linaro.org>
Subject: Re: [RFC] sched,livepatch: call klp_try_switch_task in __cond_resched
Date: Sun, 8 May 2022 22:41:01 +0200 [thread overview]
Message-ID: <20220508204101.GB76023@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <901aa9a48ef02eeec73dedf051dd0b14436ac22f.camel@fb.com>
On Sat, May 07, 2022 at 07:18:51PM +0000, Rik van Riel wrote:
> Huh, I just looked at that, and the x86 should_resched()
> only seems to check that we _can_ resched, not whether
> we should...
>
>
> /*
> * Returns true when we need to resched and can (barring IRQ state).
> */
> static __always_inline bool should_resched(int preempt_offset)
> {
> return unlikely(raw_cpu_read_4(__preempt_count) ==
> preempt_offset);
> }
>
> I wonder if that was intended, and why, or whether
> the x86 should_resched should also be checking for
> TIF_NEED_RESCHED?
No, it does what you think it should do, you're just getting confused by
the inverted PREEMPT_NEED_RESCHED bit :-)
next prev parent reply other threads:[~2022-05-08 20:41 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-07 17:46 [RFC] sched,livepatch: call klp_try_switch_task in __cond_resched Song Liu
2022-05-07 18:26 ` Rik van Riel
2022-05-07 19:04 ` Song Liu
2022-05-07 19:18 ` Rik van Riel
2022-05-08 20:41 ` Peter Zijlstra [this message]
2022-05-09 1:07 ` Rik van Riel
2022-05-09 7:04 ` Peter Zijlstra
2022-05-09 8:06 ` Song Liu
2022-05-09 9:38 ` Peter Zijlstra
2022-05-09 14:13 ` Rik van Riel
2022-05-09 15:22 ` Petr Mladek
2022-05-09 15:07 ` Petr Mladek
2022-05-09 16:22 ` Song Liu
2022-05-10 7:56 ` Petr Mladek
2022-05-10 13:33 ` Rik van Riel
2022-05-10 15:44 ` Petr Mladek
2022-05-10 16:07 ` Rik van Riel
2022-05-10 16:52 ` Josh Poimboeuf
2022-05-10 18:07 ` Rik van Riel
2022-05-10 18:42 ` Josh Poimboeuf
2022-05-10 19:45 ` Song Liu
2022-05-10 23:04 ` Josh Poimboeuf
2022-05-10 23:57 ` Song Liu
2022-05-11 0:33 ` Josh Poimboeuf
2022-05-11 9:24 ` Petr Mladek
2022-05-11 16:33 ` Song Liu
2022-05-12 4:07 ` Josh Poimboeuf
2022-05-13 12:33 ` Petr Mladek
2022-05-13 13:34 ` Peter Zijlstra
2022-05-11 0:35 ` Rik van Riel
2022-05-11 0:37 ` Josh Poimboeuf
2022-05-11 0:46 ` Rik van Riel
2022-05-11 1:12 ` Josh Poimboeuf
2022-05-11 18:09 ` Rik van Riel
2022-05-12 3:59 ` Josh Poimboeuf
2022-05-09 15:52 ` [RFC] sched,livepatch: call stop_one_cpu in klp_check_and_switch_task Rik van Riel
2022-05-09 16:28 ` Song Liu
2022-05-09 18:00 ` Josh Poimboeuf
2022-05-09 19:10 ` Rik van Riel
2022-05-09 19:17 ` Josh Poimboeuf
2022-05-09 19:49 ` Rik van Riel
2022-05-09 20:09 ` Josh Poimboeuf
2022-05-10 0:32 ` Song Liu
2022-05-10 9:35 ` Peter Zijlstra
2022-05-10 1:48 ` Rik van Riel
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