From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Benjamin Serebrin <serebrin@google.com>,
Ingo Molnar <mingo@kernel.org>, Rik van Riel <riel@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>,
Mel Gorman <mgorman@suse.de>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH RFC v6] x86,mm,sched: make lazy TLB mode even lazier
Date: Fri, 9 Sep 2016 09:44:56 +0200 [thread overview]
Message-ID: <20160909074456.GD10153@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CALCETrXAppLAsMj4k8LbhnQYsBJ0ui2Yzvp1R5WsZbaSnSS2Ug@mail.gmail.com>
On Thu, Sep 08, 2016 at 09:39:45PM -0700, Andy Lutomirski wrote:
> If they're busy threads, shouldn't the yield return immediately
> because the threads are still ready to run? Lazy TLB won't do much
> unless you get the kernel in some state where it's running in the
> context of a different kernel thread and hasn't switched to
> swapper_pg_dir. IIRC idle works like that, but you'd need to actually
> sleep to go idle.
Right, a task doing:
for (;;) sched_yield();
esp. when its the only runnable thread on the CPU, is a busy thread. It
will not enter switch_mm(), which was where the invalidate hook was
placed IIRC.
next prev parent reply other threads:[~2016-09-09 7:45 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-25 19:04 [PATCH RFC UGLY] x86,mm,sched: make lazy TLB mode even lazier Rik van Riel
2016-08-25 19:42 ` H. Peter Anvin
2016-08-25 19:52 ` Rik van Riel
2016-08-25 20:15 ` [PATCH RFC v2] " Rik van Riel
2016-08-25 21:01 ` [PATCH RFC v3] " Rik van Riel
2016-08-27 8:03 ` Ingo Molnar
2016-08-27 23:02 ` Linus Torvalds
2016-08-30 19:53 ` [PATCH RFC v4] " Rik van Riel
2016-08-30 21:09 ` [PATCH RFC v5] " Rik van Riel
2016-08-31 16:27 ` [PATCH RFC v6] " Rik van Riel
2016-09-08 6:56 ` Ingo Molnar
2016-09-09 0:09 ` Benjamin Serebrin
2016-09-09 4:39 ` Andy Lutomirski
2016-09-09 7:44 ` Peter Zijlstra [this message]
2017-04-25 3:30 ` Andy Lutomirski
2016-08-29 15:24 ` [PATCH RFC v3] " Rik van Riel
2016-08-29 16:08 ` [PATCH RFC UGLY] " Rik van Riel
2016-08-28 8:11 ` Andy Lutomirski
2016-08-29 14:54 ` Rik van Riel
2016-08-29 23:55 ` Andy Lutomirski
2016-08-30 1:14 ` H. Peter Anvin
2016-08-30 18:23 ` Andy Lutomirski
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