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From: Matthew Wilcox <willy@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, Davidlohr Bueso <dave@stgolabs.net>
Subject: Re: [PATCH 5/5] hugetlbfs: Limit wait time when trying to share huge PMD
Date: Wed, 11 Sep 2019 12:57:45 -0700
Message-ID: <20190911195745.GI29434@bombadil.infradead.org> (raw)
In-Reply-To: <20190911150537.19527-6-longman@redhat.com>

On Wed, Sep 11, 2019 at 04:05:37PM +0100, Waiman Long wrote:
> To remove the unacceptable delays, we have to limit the amount of wait
> time on the mmap_sem. So the new down_write_timedlock() function is
> used to acquire the write lock on the mmap_sem with a timeout value of
> 10ms which should not cause a perceivable delay. If timeout happens,
> the task will abandon its effort to share the PMD and allocate its own
> copy instead.

If you do a v2, this is *NOT* the mmap_sem.  It's the i_mmap_rwsem
which protects a very different data structure from the mmap_sem.

> +static inline bool i_mmap_timedlock_write(struct address_space *mapping,
> +					 ktime_t timeout)
> +{
> +	return down_write_timedlock(&mapping->i_mmap_rwsem, timeout);
> +}

  parent reply index

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-11 15:05 [PATCH 0/5] hugetlbfs: Disable PMD sharing for large systems Waiman Long
2019-09-11 15:05 ` [PATCH 1/5] locking/rwsem: Add down_write_timedlock() Waiman Long
2019-09-11 15:05 ` [PATCH 2/5] locking/rwsem: Enable timeout check when spinning on owner Waiman Long
2019-09-11 15:05 ` [PATCH 3/5] locking/osq: Allow early break from OSQ Waiman Long
2019-09-11 15:05 ` [PATCH 4/5] locking/rwsem: Enable timeout check when staying in the OSQ Waiman Long
2019-09-11 15:05 ` [PATCH 5/5] hugetlbfs: Limit wait time when trying to share huge PMD Waiman Long
2019-09-11 15:14   ` Matthew Wilcox
2019-09-11 15:44     ` Waiman Long
2019-09-11 17:03       ` Mike Kravetz
2019-09-11 17:15         ` Waiman Long
2019-09-11 17:22           ` Qian Cai
2019-09-11 17:28           ` Waiman Long
2019-09-11 16:01   ` Qian Cai
2019-09-11 16:34     ` Waiman Long
2019-09-11 19:42       ` Qian Cai
2019-09-11 20:54         ` Waiman Long
2019-09-11 21:57           ` Qian Cai
2019-09-11 19:57   ` Matthew Wilcox [this message]
2019-09-11 20:51     ` Waiman Long
2019-09-12  3:26   ` Mike Kravetz
2019-09-12  3:41     ` Matthew Wilcox
2019-09-12  4:40       ` Davidlohr Bueso
2019-09-16 13:53         ` Waiman Long
2019-09-12  9:06     ` Waiman Long
2019-09-12 16:43       ` Mike Kravetz
2019-09-13 18:23         ` Waiman Long
2019-09-13  1:50 ` [PATCH 0/5] hugetlbfs: Disable PMD sharing for large systems Dave Chinner
2019-09-25  8:35   ` Peter Zijlstra

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