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Date: Wed, 18 May 2016 13:56:06 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: linux-nvdimm@...ts.01.org
Cc: Dave Hansen <dave.hansen@...ux.intel.com>,
Dave Chinner <david@...morbit.com>,
linux-kernel@...r.kernel.org, hch@....de,
linux-block@...r.kernel.org, Jeff Moyer <jmoyer@...hat.com>,
Hannes Reinecke <hare@...e.de>,
Johannes Thumshirn <jthumshirn@...e.de>,
Andrew Morton <akpm@...ux-foundation.org>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Ross Zwisler <ross.zwisler@...ux.intel.com>,
Jan Kara <jack@...e.com>
Subject: [PATCH v3 0/5] "Device DAX" for persistent memory
Changes since v2 [1]:
1/ Allow libnvdimm drivers to omit a ->remove() method (Johannes)
2/ Fix memory leak due to missing ida_destroy() in drivers/nvdimm/ and
drivers/dax/ (Johannes)
3/ Mark some dev_dbg() instances as dev_info() (Johannes)
4/ Clarify RCU usage in dax.c (Johannes), acked-by Paul.
---
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/005766.html
[2]: https://lwn.net/Articles/685107/
---
Dan Williams (5):
libnvdimm: stop requiring a driver ->remove() method
/dev/dax, pmem: direct access to persistent memory
/dev/dax, core: file operations and dax-mmap
Revert "block: enable dax for raw block devices"
libnvdimm: release ida resources
block/ioctl.c | 32 --
drivers/Kconfig | 2
drivers/Makefile | 1
drivers/dax/Kconfig | 26 ++
drivers/dax/Makefile | 4
drivers/dax/dax.c | 575 +++++++++++++++++++++++++++++++++++
drivers/dax/dax.h | 24 +
drivers/dax/pmem.c | 158 ++++++++++
drivers/nvdimm/bus.c | 9 -
drivers/nvdimm/core.c | 3
drivers/nvdimm/dimm_devs.c | 5
drivers/nvdimm/nd-core.h | 2
drivers/nvdimm/region_devs.c | 5
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
20 files changed, 852 insertions(+), 112 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
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