From: Dan Williams <dan.j.williams@intel.com>
To: linux-nvdimm@ml01.01.org
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
Dave Chinner <david@fromorbit.com>,
linux-kernel@vger.kernel.org, hch@lst.de,
linux-block@vger.kernel.org, Jeff Moyer <jmoyer@redhat.com>,
Jan Kara <jack@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
Ross Zwisler <ross.zwisler@linux.intel.com>
Subject: [PATCH v2 0/3] "Device DAX" for persistent memory
Date: Sat, 14 May 2016 23:26:18 -0700 [thread overview]
Message-ID: <146329357870.17948.14240958684074905846.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)
Changes since v1: [1]
1/ Dropped the lead in cleanup patches from this posting as they appear
on the libnvdimm-for-next branch.
2/ Fixed the needlessly overweight fault locking by replacing it with
rcu_read_lock() and drop taking the i_mmap_lock since it has no effect
or purpose. Unlike block devices the vfs does not arrange for character
device inodes to share the same address_space.
3/ Fixed the device release path since the class release method is not
called when the device is created by device_create_with_groups().
4/ Cleanups resulting from the switch to carry (struct dax_dev *) in
filp->private_date.
---
Device DAX is the device-centric analogue of Filesystem DAX
(CONFIG_FS_DAX). It allows memory ranges to be allocated and mapped
without need of an intervening file system or being bound to block
device semantics.
Why "Device DAX"?
1/ As I mentioned at LSF [2] we are starting to see platforms with
performance and feature differentiated memory ranges. Environments like
high-performance-computing and usages like in-memory databases want
exclusive allocation of a memory range with zero conflicting
kernel/metadata allocations. For dedicated applications of high
bandwidth or low latency memory device-DAX provides a predictable direct
map mechanism.
Note that this is only for the small number of "crazy" applications that
are willing to re-write to get every bit of performance. For everyone
else we, Dave Hansen and I, are looking to add a mechanism to hot-plug
device-DAX ranges into the mm to get general memory management services
(oversubscribe / migration, etc) with the understanding that it may
sacrifice some predictability.
2/ For persistent memory there are similar applications that are willing
to re-write to take full advantage of byte-addressable persistence.
This mechanism satisfies those usages that only need a pre-allocated
file to mmap.
3/ It answers Dave Chinner's call to start thinking about pmem-native
solutions. Device DAX specifically avoids block-device and file system
conflicts.
[1]: https://lists.01.org/pipermail/linux-nvdimm/2016-May/005660.html
[2]: https://lwn.net/Articles/685107/
---
Dan Williams (3):
/dev/dax, pmem: direct access to persistent memory
/dev/dax, core: file operations and dax-mmap
Revert "block: enable dax for raw block devices"
block/ioctl.c | 32 --
drivers/Kconfig | 2
drivers/Makefile | 1
drivers/dax/Kconfig | 26 ++
drivers/dax/Makefile | 4
drivers/dax/dax.c | 568 +++++++++++++++++++++++++++++++++++
drivers/dax/dax.h | 24 +
drivers/dax/pmem.c | 168 ++++++++++
fs/block_dev.c | 96 ++----
include/linux/fs.h | 8
include/uapi/linux/fs.h | 1
mm/huge_memory.c | 1
mm/hugetlb.c | 1
tools/testing/nvdimm/Kbuild | 9 +
tools/testing/nvdimm/config_check.c | 2
15 files changed, 835 insertions(+), 108 deletions(-)
create mode 100644 drivers/dax/Kconfig
create mode 100644 drivers/dax/Makefile
create mode 100644 drivers/dax/dax.c
create mode 100644 drivers/dax/dax.h
create mode 100644 drivers/dax/pmem.c
next reply other threads:[~2016-05-15 6:27 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-15 6:26 Dan Williams [this message]
2016-05-15 6:26 ` [PATCH v2 1/3] /dev/dax, pmem: direct access to persistent memory Dan Williams
2016-05-17 8:52 ` Johannes Thumshirn
2016-05-17 16:40 ` Dan Williams
2016-05-15 6:26 ` [PATCH v2 2/3] /dev/dax, core: file operations and dax-mmap Dan Williams
2016-05-17 10:57 ` Johannes Thumshirn
2016-05-17 22:19 ` Dan Williams
2016-05-18 8:07 ` Hannes Reinecke
2016-05-18 9:10 ` Paul Mackerras
2016-05-18 9:15 ` Hannes Reinecke
2016-05-18 17:12 ` Paul E. McKenney
2016-05-18 17:26 ` Dan Williams
2016-05-18 17:57 ` Paul E. McKenney
2016-05-15 6:26 ` [PATCH v2 3/3] Revert "block: enable dax for raw block devices" Dan Williams
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