From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Liang, Kan" <kan.liang@intel.com>,
Mel Gorman <mgorman@techsingularity.net>,
Mel Gorman <mgorman@suse.de>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Ingo Molnar <mingo@elte.hu>, Andi Kleen <ak@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>,
linux-mm <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] sched/wait: Break up long wake list walk
Date: Tue, 22 Aug 2017 22:53:16 +0200 [thread overview]
Message-ID: <20170822205316.GS32112@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <CA+55aFwavpFfKNW9NVgNhLggqhii-guc5aX1X5fxrPK+==id0g@mail.gmail.com>
On Tue, Aug 22, 2017 at 01:42:13PM -0700, Linus Torvalds wrote:
> +void wait_on_page_bit_or_yield(struct page *page, int bit_nr)
> +{
> + if (PageWaiters(page)) {
> + yield();
> + return;
> + }
> + wait_on_page_bit(page, bit_nr);
> +}
So _the_ problem with yield() is when you hit this with a RT task it
will busy spin and possibly not allow the task that actually has the
lock to make progress at all.
So ideally there'd be a timeout or other limit on the amount of yield().
This being bit-spinlocks leaves us very short on state to play with
though :/
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next prev parent reply other threads:[~2017-08-22 20:53 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-15 0:52 [PATCH 1/2] sched/wait: Break up long wake list walk Tim Chen
2017-08-15 0:52 ` [PATCH 2/2] sched/wait: Introduce lock breaker in wake_up_page_bit Tim Chen
2017-08-15 1:48 ` [PATCH 1/2] sched/wait: Break up long wake list walk Linus Torvalds
2017-08-15 2:27 ` Andi Kleen
2017-08-15 2:52 ` Linus Torvalds
2017-08-15 3:15 ` Andi Kleen
2017-08-15 3:28 ` Linus Torvalds
2017-08-15 19:05 ` Tim Chen
2017-08-15 19:41 ` Linus Torvalds
2017-08-15 19:47 ` Linus Torvalds
2017-08-15 22:47 ` Davidlohr Bueso
2017-08-15 22:56 ` Linus Torvalds
2017-08-15 22:57 ` Linus Torvalds
2017-08-15 23:50 ` Linus Torvalds
2017-08-16 23:22 ` Eric W. Biederman
2017-08-17 16:17 ` Liang, Kan
2017-08-17 16:25 ` Linus Torvalds
2017-08-17 20:18 ` Liang, Kan
2017-08-17 20:44 ` Linus Torvalds
2017-08-18 12:23 ` Mel Gorman
2017-08-18 14:20 ` Liang, Kan
2017-08-18 14:46 ` Mel Gorman
2017-08-18 16:36 ` Tim Chen
2017-08-18 16:45 ` Andi Kleen
2017-08-18 16:53 ` Liang, Kan
2017-08-18 17:48 ` Linus Torvalds
2017-08-18 18:54 ` Mel Gorman
2017-08-18 19:14 ` Linus Torvalds
2017-08-18 19:58 ` Andi Kleen
2017-08-18 20:10 ` Linus Torvalds
2017-08-21 18:32 ` Mel Gorman
2017-08-21 18:56 ` Liang, Kan
2017-08-22 17:23 ` Liang, Kan
2017-08-22 18:19 ` Linus Torvalds
2017-08-22 18:25 ` Linus Torvalds
2017-08-22 18:56 ` Peter Zijlstra
2017-08-22 19:15 ` Linus Torvalds
2017-08-22 19:08 ` Peter Zijlstra
2017-08-22 19:30 ` Linus Torvalds
2017-08-22 19:37 ` Andi Kleen
2017-08-22 21:08 ` Christopher Lameter
2017-08-22 21:24 ` Andi Kleen
2017-08-22 22:52 ` Linus Torvalds
2017-08-22 23:19 ` Linus Torvalds
2017-08-23 14:51 ` Liang, Kan
2017-08-22 19:55 ` Liang, Kan
2017-08-22 20:42 ` Linus Torvalds
2017-08-22 20:53 ` Peter Zijlstra [this message]
2017-08-22 20:58 ` Linus Torvalds
2017-08-23 14:49 ` Liang, Kan
2017-08-23 15:58 ` Tim Chen
2017-08-23 18:17 ` Linus Torvalds
2017-08-23 20:55 ` Liang, Kan
2017-08-23 23:30 ` Linus Torvalds
2017-08-24 17:49 ` Tim Chen
2017-08-24 18:16 ` Linus Torvalds
2017-08-24 20:44 ` Mel Gorman
2017-08-25 16:44 ` Tim Chen
2017-08-23 16:04 ` Mel Gorman
2017-08-18 20:05 ` Andi Kleen
2017-08-18 20:29 ` Linus Torvalds
2017-08-18 20:29 ` Liang, Kan
2017-08-18 20:34 ` Linus Torvalds
2017-08-18 16:55 ` Linus Torvalds
2017-08-18 13:06 ` Liang, Kan
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