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From: Dan Williams <dan.j.williams@intel.com>
To: Jan Kara <jack@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
	Josh Triplett <josh.triplett@intel.com>,
	Mike Snitzer <snitzer@redhat.com>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	Matthew Wilcox <mawilcox@microsoft.com>,
	Dave Chinner <david@fromorbit.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Christoph Hellwig <hch@lst.de>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	linux-nvdimm <linux-nvdimm@lists.01.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings
Date: Mon, 9 Apr 2018 09:51:33 -0700	[thread overview]
Message-ID: <CAPcyv4gzJ4gcWgwOOmER1z7zsWR+X2zao-tMh8TjN9tx2kg_0g@mail.gmail.com> (raw)
In-Reply-To: <20180409164944.6u7i4wgbp6yihvin@quack2.suse.cz>

On Mon, Apr 9, 2018 at 9:49 AM, Jan Kara <jack@suse.cz> wrote:
> On Sat 07-04-18 12:38:24, Dan Williams wrote:
[..]
>> I wonder if this can be trivially solved by using srcu. I.e. we don't
>> need to wait for a global quiescent state, just a
>> get_user_pages_fast() quiescent state. ...or is that an abuse of the
>> srcu api?
>
> Well, I'd rather use the percpu rwsemaphore (linux/percpu-rwsem.h) than
> SRCU. It is a more-or-less standard locking mechanism rather than relying
> on implementation properties of SRCU which is a data structure protection
> method. And the overhead of percpu rwsemaphore for your use case should be
> about the same as that of SRCU.

I was just about to ask that. Yes, it seems they would share similar
properties and it would be better to use the explicit implementation
rather than a side effect of srcu.
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  reply	other threads:[~2018-04-09 16:51 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-31  4:02 [PATCH v8 00/18] dax: fix dma vs truncate/hole-punch Dan Williams
2018-03-31  4:02 ` [PATCH v8 01/18] dax: store pfns in the radix Dan Williams
2018-03-31  4:02 ` [PATCH v8 02/18] fs, dax: prepare for dax-specific address_space_operations Dan Williams
2018-03-31  4:02 ` [PATCH v8 03/18] block, dax: remove dead code in blkdev_writepages() Dan Williams
2018-03-31  4:02 ` [PATCH v8 04/18] xfs, dax: introduce xfs_dax_aops Dan Williams
2018-03-31  4:02 ` [PATCH v8 05/18] ext4, dax: introduce ext4_dax_aops Dan Williams
2018-04-03 11:50   ` Jan Kara
2018-03-31  4:02 ` [PATCH v8 06/18] ext2, dax: introduce ext2_dax_aops Dan Williams
2018-04-03 11:51   ` Jan Kara
2018-03-31  4:02 ` [PATCH v8 07/18] fs, dax: use page->mapping to warn if truncate collides with a busy page Dan Williams
2018-03-31  4:02 ` [PATCH v8 08/18] dax: introduce CONFIG_DAX_DRIVER Dan Williams
2018-03-31  4:02 ` [PATCH v8 09/18] dax, dm: allow device-mapper to operate without dax support Dan Williams
2018-03-31  4:03 ` [PATCH v8 10/18] dax, dm: introduce ->fs_{claim, release}() dax_device infrastructure Dan Williams
2018-04-03 18:24   ` Dan Williams
2018-04-03 19:39     ` Mike Snitzer
2018-04-03 19:47       ` Dan Williams
2018-04-03 20:36         ` [PATCH v9] " Dan Williams
2018-04-03 21:13           ` Mike Snitzer
2018-03-31  4:03 ` [PATCH v8 11/18] mm, dax: enable filesystems to trigger dev_pagemap ->page_free callbacks Dan Williams
2018-04-04 21:23   ` [v8, " Andrei Vagin
2018-04-04 21:27     ` Dan Williams
2018-04-04 21:35       ` Dan Williams
2018-04-04 23:19         ` Stephen Rothwell
2018-04-04 21:40     ` Andrei Vagin
2018-03-31  4:03 ` [PATCH v8 12/18] memremap: split devm_memremap_pages() and memremap() infrastructure Dan Williams
2018-03-31  4:03 ` [PATCH v8 13/18] mm, dev_pagemap: introduce CONFIG_DEV_PAGEMAP_OPS Dan Williams
2018-03-31  4:03 ` [PATCH v8 14/18] memremap: mark devm_memremap_pages() EXPORT_SYMBOL_GPL Dan Williams
2018-03-31  4:03 ` [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings Dan Williams
2018-04-04  9:46   ` Jan Kara
2018-04-04 10:06     ` Jan Kara
2018-04-04 14:12     ` Dan Williams
2018-04-07 19:38     ` Dan Williams
2018-04-08  3:11       ` Paul E. McKenney
2018-04-09 16:39         ` Jan Kara
2018-04-09 18:14           ` Paul E. McKenney
2018-04-09 16:49       ` Jan Kara
2018-04-09 16:51         ` Dan Williams [this message]
2018-04-13 22:03           ` Dan Williams
2018-04-13 22:48             ` Paul E. McKenney
2018-04-19 10:44             ` Jan Kara
2018-04-20  3:00               ` Dan Williams
2018-03-31  4:03 ` [PATCH v8 16/18] xfs: prepare xfs_break_layouts() to be called with XFS_MMAPLOCK_EXCL Dan Williams
2018-03-31  4:03 ` [PATCH v8 17/18] xfs: prepare xfs_break_layouts() for another layout type Dan Williams
2018-03-31  4:03 ` [PATCH v8 18/18] xfs, dax: introduce xfs_break_dax_layouts() Dan Williams
2018-04-04  9:55   ` Jan Kara

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