From: Josh Poimboeuf <jpoimboe@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Ankur Arora <ankur.a.arora@oracle.com>,
linux-kernel@vger.kernel.org, tglx@linutronix.de,
peterz@infradead.org, torvalds@linux-foundation.org,
paulmck@kernel.org, linux-mm@kvack.org, x86@kernel.org,
akpm@linux-foundation.org, luto@kernel.org, bp@alien8.de,
dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com,
juri.lelli@redhat.com, vincent.guittot@linaro.org,
willy@infradead.org, mgorman@suse.de, jon.grimm@amd.com,
bharata@amd.com, raghavendra.kt@amd.com,
boris.ostrovsky@oracle.com, konrad.wilk@oracle.com,
jgross@suse.com, andrew.cooper3@citrix.com, mingo@kernel.org,
bristot@kernel.org, mathieu.desnoyers@efficios.com,
geert@linux-m68k.org, glaubitz@physik.fu-berlin.de,
anton.ivanov@cambridgegreys.com, mattst88@gmail.com,
krypton@ulrich-teichert.org, David.Laight@ACULAB.COM,
richard@nod.at, mjguzik@gmail.com, Jiri Kosina <jikos@kernel.org>,
Miroslav Benes <mbenes@suse.cz>, Petr Mladek <pmladek@suse.com>,
Joe Lawrence <joe.lawrence@redhat.com>,
live-patching@vger.kernel.org
Subject: Re: [RFC PATCH 07/86] Revert "livepatch,sched: Add livepatch task switching to cond_resched()"
Date: Thu, 9 Nov 2023 09:26:37 -0800 [thread overview]
Message-ID: <20231109172637.ayue3jexgdxd53tu@treble> (raw)
In-Reply-To: <20231107181609.7e9e9dcc@gandalf.local.home>
On Tue, Nov 07, 2023 at 06:16:09PM -0500, Steven Rostedt wrote:
> On Tue, 7 Nov 2023 13:56:53 -0800
> Ankur Arora <ankur.a.arora@oracle.com> wrote:
>
> > This reverts commit e3ff7c609f39671d1aaff4fb4a8594e14f3e03f8.
> >
> > Note that removing this commit reintroduces "live patches failing to
> > complete within a reasonable amount of time due to CPU-bound kthreads."
> >
> > Unfortunately this fix depends quite critically on PREEMPT_DYNAMIC and
> > existence of cond_resched() so this will need an alternate fix.
We definitely don't want to introduce a regression, something will need
to be figured out before removing cond_resched().
We could hook into preempt_schedule_irq(), but that wouldn't work for
non-ORC.
Another option would be to hook into schedule(). Then livepatch could
set TIF_NEED_RESCHED on remaining unpatched tasks. But again if they go
through the preemption path then we have the same problem for non-ORC.
Worst case we'll need to sprinkle cond_livepatch() everywhere :-/
--
Josh
next prev parent reply other threads:[~2023-11-09 17:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20231107215742.363031-1-ankur.a.arora@oracle.com>
[not found] ` <20231107215742.363031-8-ankur.a.arora@oracle.com>
2023-11-07 23:16 ` [RFC PATCH 07/86] Revert "livepatch,sched: Add livepatch task switching to cond_resched()" Steven Rostedt
2023-11-08 4:55 ` Ankur Arora
2023-11-09 17:26 ` Josh Poimboeuf [this message]
2023-11-09 17:31 ` Steven Rostedt
2023-11-09 17:51 ` Josh Poimboeuf
2023-11-09 22:50 ` Ankur Arora
2023-11-09 23:47 ` Josh Poimboeuf
2023-11-10 0:46 ` Ankur Arora
2023-11-10 0:56 ` Steven Rostedt
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