From: Linus Torvalds <torvalds@linux-foundation.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>,
Mel Gorman <mgorman@techsingularity.net>,
Peter Zijlstra <peterz@infradead.org>,
Rik van Riel <riel@redhat.com>, Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH 2/2] mm: add PageWaiters bit to indicate waitqueue should be checked
Date: Wed, 2 Nov 2016 09:18:37 -0600 [thread overview]
Message-ID: <CA+55aFxhxfevU1uKwHmPheoU7co4zxxcri+AiTpKz=1_Nd0_ig@mail.gmail.com> (raw)
In-Reply-To: <20161102070346.12489-3-npiggin@gmail.com>
On Wed, Nov 2, 2016 at 1:03 AM, Nicholas Piggin <npiggin@gmail.com> wrote:
> + __wake_up_locked_key(q, TASK_NORMAL, &key);
> + if (!waitqueue_active(q) || !key.page_match) {
> + ClearPageWaiters(page);
Is that "page_match" optimization really worth it? I'd rather see
numbers for that particular optimization. I'd rather see the
contention bit being explicitly not precise.
Also, it would be lovely to get numbers against the plain 4.8
situation with the per-zone waitqueues. Maybe that used to help your
workload, so the 2.2% improvement might be partly due to me breaking
performance on your machine.
But other than that this all looks fine to me.
Linus
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next prev parent reply other threads:[~2016-11-02 15:18 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-02 7:03 [RFC][PATCH 0/2] optimise unlock_page / end_page_writeback Nicholas Piggin
2016-11-02 7:03 ` [PATCH 1/2] mm: Use owner_priv bit for PageSwapCache, valid when PageSwapBacked Nicholas Piggin
2016-11-04 2:20 ` Hugh Dickins
2016-11-11 0:58 ` Nicholas Piggin
2016-11-02 7:03 ` [PATCH 2/2] mm: add PageWaiters bit to indicate waitqueue should be checked Nicholas Piggin
2016-11-02 7:31 ` Kirill A. Shutemov
2016-11-02 7:50 ` Nicholas Piggin
2016-11-02 7:58 ` Kirill A. Shutemov
2016-11-02 8:12 ` Nicholas Piggin
2016-11-02 8:33 ` Kirill A. Shutemov
2016-11-02 8:40 ` Nicholas Piggin
2016-11-02 9:04 ` Kirill A. Shutemov
2016-11-02 15:18 ` Linus Torvalds [this message]
2016-11-03 3:46 ` Nicholas Piggin
2016-11-03 15:49 ` Linus Torvalds
2016-11-04 2:40 ` Nicholas Piggin
2016-11-04 7:29 ` Nicholas Piggin
2016-11-04 15:59 ` Linus Torvalds
2016-11-07 3:04 ` Nicholas Piggin
2016-11-04 2:31 ` [lkp] [mm] 731b9bc419: kernel BUG at include/linux/page-flags.h:259! kernel test robot
2016-11-04 2:47 ` Nicholas Piggin
2016-12-21 15:19 [PATCH 0/2] respin of PageWaiters patch Nicholas Piggin
2016-12-21 15:19 ` [PATCH 2/2] mm: add PageWaiters bit to indicate waitqueue should be checked Nicholas Piggin
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