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From: Christoph Hellwig <hch@infradead.org>
To: John Hubbard <jhubbard@nvidia.com>
Cc: Dave Chinner <david@fromorbit.com>,
	Matthew Wilcox <willy@infradead.org>,
	Michal Hocko <mhocko@kernel.org>,
	Christopher Lameter <cl@linux.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Dan Williams <dan.j.williams@intel.com>, Jan Kara <jack@suse.cz>,
	linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-rdma <linux-rdma@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 4/6] mm: introduce page->dma_pinned_flags, _count
Date: Sat, 13 Oct 2018 09:47:41 -0700	[thread overview]
Message-ID: <20181013164740.GA6593@infradead.org> (raw)
In-Reply-To: <7c2e3b54-0b1d-6726-a508-804ef8620cfd@nvidia.com>

On Sat, Oct 13, 2018 at 12:34:12AM -0700, John Hubbard wrote:
> In patch 6/6, pin_page_for_dma(), which is called at the end of get_user_pages(),
> unceremoniously rips the pages out of the LRU, as a prerequisite to using
> either of the page->dma_pinned_* fields. 
> 
> The idea is that LRU is not especially useful for this situation anyway,
> so we'll just make it one or the other: either a page is dma-pinned, and
> just hanging out doing RDMA most likely (and LRU is less meaningful during that
> time), or it's possibly on an LRU list.

Have you done any benchmarking what this does to direct I/O performance,
especially for small I/O directly to a (fast) block device?

  reply	other threads:[~2018-10-13 16:48 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-12  6:00 [PATCH 0/6] RFC: gup+dma: tracking dma-pinned pages john.hubbard
2018-10-12  6:00 ` [PATCH 1/6] mm: get_user_pages: consolidate error handling john.hubbard
2018-10-12  6:30   ` Balbir Singh
2018-10-12 22:45     ` John Hubbard
2018-10-12  6:00 ` [PATCH 2/6] mm: introduce put_user_page*(), placeholder versions john.hubbard
2018-10-12  7:35   ` Balbir Singh
2018-10-12 22:31     ` John Hubbard
2018-10-12  6:00 ` [PATCH 3/6] infiniband/mm: convert put_page() to put_user_page*() john.hubbard
2018-10-12  6:00 ` [PATCH 4/6] mm: introduce page->dma_pinned_flags, _count john.hubbard
2018-10-12 10:56   ` Balbir Singh
2018-10-13  0:15     ` John Hubbard
2018-10-24 11:00       ` Balbir Singh
2018-11-02 23:27         ` John Hubbard
2018-10-13  3:55   ` Dave Chinner
2018-10-13  7:34     ` John Hubbard
2018-10-13 16:47       ` Christoph Hellwig [this message]
2018-10-13 21:19         ` John Hubbard
2018-11-05  7:10         ` John Hubbard
2018-11-05  9:54           ` Jan Kara
2018-11-06  0:26             ` John Hubbard
2018-11-06  2:47               ` Dave Chinner
2018-11-06 11:00                 ` Jan Kara
2018-11-06 20:41                   ` Dave Chinner
2018-11-07  6:36                     ` John Hubbard
2018-10-13 23:01       ` Dave Chinner
2018-10-16  8:51         ` Jan Kara
2018-10-17  1:48           ` John Hubbard
2018-10-17 11:09             ` Michal Hocko
2018-10-18  0:03               ` John Hubbard
2018-10-19  8:11                 ` Michal Hocko
2018-10-12  6:00 ` [PATCH 5/6] mm: introduce zone_gup_lock, for dma-pinned pages john.hubbard
2018-10-12  6:00 ` [PATCH 6/6] mm: track gup pages with page->dma_pinned_* fields john.hubbard
2018-10-12 11:07   ` Balbir Singh
2018-10-13  0:33     ` John Hubbard

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