From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: Jann Horn <jannh@google.com>, Peter Oskolkov <posk@google.com>,
Peter Oskolkov <posk@posk.io>, Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Paul Turner <pjt@google.com>, Ben Segall <bsegall@google.com>,
Andrei Vagin <avagin@google.com>,
Thierry Delisle <tdelisle@uwaterloo.ca>
Subject: Re: [PATCH 2/4 v0.5] sched/umcg: RFC: add userspace atomic helpers
Date: Wed, 15 Sep 2021 21:10:23 +0200 [thread overview]
Message-ID: <20210915191023.GF4323@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <CALCETrUnnHN0dyx02ewuRu=_TZ+cD=HaEzNs34ADNbWps1tTBw@mail.gmail.com>
On Wed, Sep 15, 2021 at 09:50:41AM -0700, Andy Lutomirski wrote:
> What's the precise problem? The code would be roughly:
>
> if (try_pin_the_page) {
> write it;
> unpin;
> } else {
> do nothing -- .fault will fill in the correct contents.
> }
>
> The time this takes is nondeterministic, but it's bounded and short.
You can't do this from sched_submit_work(), you might already hold
mmap_sem. Hence the suggestion to, for UMCG registered threads, pin the
page(s) on syscall-enter and unpin on either schedule() or
syscall-return.
next prev parent reply other threads:[~2021-09-15 19:12 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-08 18:49 [PATCH 0/4 v0.5] sched/umcg: RFC UMCG patchset Peter Oskolkov
2021-09-08 18:49 ` [PATCH 1/4 v0.5] sched/umcg: add WF_CURRENT_CPU and externise ttwu Peter Oskolkov
2021-09-08 18:49 ` [PATCH 2/4 v0.5] sched/umcg: RFC: add userspace atomic helpers Peter Oskolkov
2021-09-08 23:38 ` Jann Horn
2021-09-09 1:16 ` Jann Horn
2021-09-09 19:06 ` Peter Oskolkov
2021-09-09 21:20 ` Jann Horn
2021-09-09 22:09 ` Peter Oskolkov
2021-09-09 23:13 ` Jann Horn
2021-09-14 16:52 ` Andy Lutomirski
2021-09-14 18:11 ` Peter Zijlstra
2021-09-14 18:40 ` Andy Lutomirski
2021-09-15 15:42 ` Peter Zijlstra
2021-09-15 16:50 ` Andy Lutomirski
2021-09-15 19:10 ` Peter Zijlstra [this message]
2021-09-14 8:07 ` Peter Zijlstra
2021-09-14 16:29 ` Peter Oskolkov
2021-09-14 18:04 ` Peter Zijlstra
2021-09-14 18:15 ` Peter Zijlstra
2021-09-14 18:29 ` Peter Oskolkov
2021-09-14 18:48 ` Peter Oskolkov
2021-09-08 18:49 ` [PATCH 3/4 v0.5] sched/umcg: RFC: implement UMCG syscalls Peter Oskolkov
2021-09-09 1:39 ` Jann Horn
2021-09-14 16:51 ` Peter Oskolkov
2021-09-08 18:49 ` [PATCH 4/4 v0.5] sched/umcg: add Documentation/userspace-api/umcg.rst Peter Oskolkov
2021-09-14 16:35 ` Tao Zhou
2021-09-14 16:57 ` Peter Oskolkov
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