The ZIO pipeline has been modified to allow for external,
alternative implementations of existing operations to be
used. The original ZFS functions remain in the code as
fallback in case the external implementation fails.
Definitions:
Accelerator - an entity (usually hardware) that is
intended to accelerate operations
Offloader - synonym of accelerator; used interchangeably
Data Processing Unit Services Module (DPUSM)
- https://github.com/hpc/dpusm
- defines a "provider API" for accelerator
vendors to set up
- defines a "user API" for accelerator consumers
to call
- maintains list of providers and coordinates
interactions between providers and consumers.
Provider - a DPUSM wrapper for an accelerator's API
Offload - moving data from ZFS/memory to the accelerator
Onload - the opposite of offload
In order for Z.I.A. to be extensible, it does not directly
communicate with a fixed accelerator. Rather, Z.I.A. acquires
a handle to a DPUSM, which is then used to acquire handles
to providers.
Using ZFS with Z.I.A.:
1. Build and start the DPUSM
2. Implement, build, and register a provider with the DPUSM
3. Reconfigure ZFS with '--with-zia=<DPUSM root>'
4. Rebuild and start ZFS
5. Create a zpool
6. Select the provider
zpool set zia_provider=<provider name> <zpool>
7. Select operations to offload
zpool set zia_<property>=on <zpool>
The operations that have been modified are:
- compression
- non-raw-writes only
- decompression
- checksum
- not handling embedded checksums
- checksum compute and checksum error call the same function
- raidz
- generation
- reconstruction
- vdev_file
- open
- write
- close
- vdev_disk
- open
- invalidate
- write
- flush
- close
Successful operations do not bring data back into memory after
they complete, allowing for subsequent offloader operations
reuse the data. This results in only one data movement per ZIO
at the beginning of a pipeline that is necessary for getting
data from ZFS to the accelerator.
When errors ocurr and the offloaded data is still accessible,
the offloaded data will be onloaded (or dropped if it still
matches the in-memory copy) for that ZIO pipeline stage and
processed with ZFS. This will cause thrashing if a later
operation offloads data. This should not happen often, as
constant errors (resulting in data movement) is not expected
to be the norm.
Unrecoverable errors such as hardware failures will trigger
pipeline restarts (if necessary) in order to complete the
original ZIO using the software path.
The modifications to ZFS can be thought of as two sets of changes:
- The ZIO write pipeline
- compression, checksum, RAIDZ generation, and write
- Each stage starts by offloading data that was not
previously offloaded
- This allows for ZIOs to be offloaded at any point
in the pipeline
- Resilver
- vdev_raidz_io_done (RAIDZ reconstruction, checksum, and
RAIDZ generation), and write
- Because the core of resilver is vdev_raidz_io_done, data
is only offloaded once at the beginning of
vdev_raidz_io_done
- Errors cause data to be onloaded, but will not
re-offload in subsequent steps within resilver
- Write is a separate ZIO pipeline stage, so it will
attempt to offload data
The zio_decompress function has been modified to allow for
offloading but the ZIO read pipeline as a whole has not, so it
is not part of the above list.
An example provider implementation can be found in
module/zia-software-provider
- The provider's "hardware" is actually software - data is
"offloaded" to memory not owned by ZFS
- Calls ZFS functions in order to not reimplement operations
- Has kernel module parameters that can be used to trigger
ZIA_ACCELERATOR_DOWN states for testing pipeline restarts.
abd_t, raidz_row_t, and vdev_t have each been given an additional
"void *<prefix>_zia_handle" member. These opaque handles point to
data that is located on an offloader. abds are still allocated,
but their payloads are expected to diverge from the offloaded copy
as operations are run.
Encryption and deduplication are disabled for zpools with Z.I.A.
operations enabled
Aggregation is disabled for offloaded abds
RPMs will build with Z.I.A.
Signed-off-by: Jason Lee <jasonlee@lanl.gov>
This commit changes the frontend zio_compress_data and
zio_decompress_data APIs to take ABD points instead of buffer pointers.
All callers are updated to match. Any that already have an appropriate
ABD nearby now use it directly, while at the rest we create an one.
Internally, the ABDs are passed through to the provider directly.
Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
This commit changes the provider compress and decompress API to take ABD
pointers instead of buffer pointers for both data source and
destination. It then updates all providers to match.
This doesn't actually change the providers to do chunked compression,
just changes the API to allow such an update in the future. Helper
macros are added to easily adapt the ABD functions to their buffer-based
implementations.
Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
This is mostly to make searching easier.
Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Hole detection in the zio compression code allows us to
opportunistically skip compression on holes. We can go a step further
by not doing memory allocations on holes either.
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Richard Yao <richard.yao@klarasystems.com>
Sponsored-by: Wasabi Technology, Inc.
Closes#14500
Some header files define structures like this one:
typedef const struct zio_checksum_info {
/* ... */
const char *ci_name;
} zio_abd_checksum_func_t;
So we can use `zio_abd_checksum_func_t` for const declarations now.
It's not needed that we use the `const` qualifier again like this:
`const zio_abd_checksum_func_t *varname;`
This patch solves the double const qualifiers, which were found by
smatch.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Tino Reichardt <milky-zfs@mcmilk.de>
Closes#13961
This PR adds two new compression types, based on ZStandard:
- zstd: A basic ZStandard compression algorithm Available compression.
Levels for zstd are zstd-1 through zstd-19, where the compression
increases with every level, but speed decreases.
- zstd-fast: A faster version of the ZStandard compression algorithm
zstd-fast is basically a "negative" level of zstd. The compression
decreases with every level, but speed increases.
Available compression levels for zstd-fast:
- zstd-fast-1 through zstd-fast-10
- zstd-fast-20 through zstd-fast-100 (in increments of 10)
- zstd-fast-500 and zstd-fast-1000
For more information check the man page.
Implementation details:
Rather than treat each level of zstd as a different algorithm (as was
done historically with gzip), the block pointer `enum zio_compress`
value is simply zstd for all levels, including zstd-fast, since they all
use the same decompression function.
The compress= property (a 64bit unsigned integer) uses the lower 7 bits
to store the compression algorithm (matching the number of bits used in
a block pointer, as the 8th bit was borrowed for embedded block
pointers). The upper bits are used to store the compression level.
It is necessary to be able to determine what compression level was used
when later reading a block back, so the concept used in LZ4, where the
first 32bits of the on-disk value are the size of the compressed data
(since the allocation is rounded up to the nearest ashift), was
extended, and we store the version of ZSTD and the level as well as the
compressed size. This value is returned when decompressing a block, so
that if the block needs to be recompressed (L2ARC, nop-write, etc), that
the same parameters will be used to result in the matching checksum.
All of the internal ZFS code ( `arc_buf_hdr_t`, `objset_t`,
`zio_prop_t`, etc.) uses the separated _compress and _complevel
variables. Only the properties ZAP contains the combined/bit-shifted
value. The combined value is split when the compression_changed_cb()
callback is called, and sets both objset members (os_compress and
os_complevel).
The userspace tools all use the combined/bit-shifted value.
Additional notes:
zdb can now also decode the ZSTD compression header (flag -Z) and
inspect the size, version and compression level saved in that header.
For each record, if it is ZSTD compressed, the parameters of the decoded
compression header get printed.
ZSTD is included with all current tests and new tests are added
as-needed.
Per-dataset feature flags now get activated when the property is set.
If a compression algorithm requires a feature flag, zfs activates the
feature when the property is set, rather than waiting for the first
block to be born. This is currently only used by zstd but can be
extended as needed.
Portions-Sponsored-By: The FreeBSD Foundation
Co-authored-by: Allan Jude <allanjude@freebsd.org>
Co-authored-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Sebastian Gottschall <s.gottschall@dd-wrt.com>
Co-authored-by: Kjeld Schouten-Lebbing <kjeld@schouten-lebbing.nl>
Co-authored-by: Michael Niewöhner <foss@mniewoehner.de>
Signed-off-by: Allan Jude <allan@klarasystems.com>
Signed-off-by: Allan Jude <allanjude@freebsd.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Sebastian Gottschall <s.gottschall@dd-wrt.com>
Signed-off-by: Kjeld Schouten-Lebbing <kjeld@schouten-lebbing.nl>
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Closes#6247Closes#9024Closes#10277Closes#10278
`lz4_decompress_abd` is declared in zio_compress.h but it is not defined
anywhere. The declaration should be removed.
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed-by: Allan Jude <allanjude@freebsd.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
External-issue: DLPX-47477
Closes#8894
3742 zfs comments need cleaner, more consistent style
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Eric Schrock <eric.schrock@delphix.com>
Approved by: Christopher Siden <christopher.siden@delphix.com>
References:
https://www.illumos.org/issues/3742illumos/illumos-gate@f717074149
Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775
Porting notes:
1. The change to zfs_vfsops.c was dropped because it involves
zfs_mount_label_policy, which does not exist in the Linux port.
Linus Torvalds merged LZ4 into Linux 3.11. This causes a conflict
whenever CONFIG_LZ4_DECOMPRESS=y or CONFIG_LZ4_COMPRESS=y are set in the
kernel's .config. We rename the symbols to avoid the conflict.
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1789
The PaX team modified the kernel's modpost to report writeable function
pointers as section mismatches because they are potential exploit
targets. We could ignore the warnings, but their presence can obscure
actual issues. Proper const correctness can also catch programming
mistakes.
Building the kernel modules against a PaX/GrSecurity patched Linux 3.4.2
kernel reports 133 section mismatches prior to this patch. This patch
eliminates 130 of them. The quantity of writeable function pointers
eliminated by constifying each structure is as follows:
vdev_opts_t 52
zil_replay_func_t 24
zio_compress_info_t 24
zio_checksum_info_t 9
space_map_ops_t 7
arc_byteswap_func_t 5
The remaining 3 writeable function pointers cannot be addressed by this
patch. 2 of them are in zpl_fs_type. The kernel's sget function requires
that this be non-const. The final writeable function pointer is created
by SPL_SHRINKER_DECLARE. The kernel's set_shrinker() and
remove_shrinker() functions also require that this be non-const.
Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1300
3035 LZ4 compression support in ZFS and GRUB
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Christopher Siden <csiden@delphix.com>
References:
illumos/illumos-gate@a6f561b4aehttps://www.illumos.org/issues/3035http://wiki.illumos.org/display/illumos/LZ4+Compression+In+ZFS
This patch has been slightly modified from the upstream Illumos
version to be compatible with Linux. Due to the very limited
stack space in the kernel a lz4 workspace kmem cache is used.
Since we are using gcc we are also able to take advantage of the
gcc optimized __builtin_ctz functions.
Support for GRUB has been dropped from this patch. That code
is available but those changes will need to made to the upstream
GRUB package.
Lastly, several hunks of dead code were dropped for clarity. They
include the functions real_LZ4_uncompress(), LZ4_compressBound()
and the Visual Studio specific hunks wrapped in _MSC_VER.
Ported-by: Eric Dillmann <eric@jave.fr>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1217
One of the neat tricks an autoconf style project is capable of
is allow configurion/building in a directory other than the
source directory. The major advantage to this is that you can
build the project various different ways while making changes
in a single source tree.
For example, this project is designed to work on various different
Linux distributions each of which work slightly differently. This
means that changes need to verified on each of those supported
distributions perferably before the change is committed to the
public git repo.
Using nfs and custom build directories makes this much easier.
I now have a single source tree in nfs mounted on several different
systems each running a supported distribution. When I make a
change to the source base I suspect may break things I can
concurrently build from the same source on all the systems each
in their own subdirectory.
wget -c http://github.com/downloads/behlendorf/zfs/zfs-x.y.z.tar.gz
tar -xzf zfs-x.y.z.tar.gz
cd zfs-x-y-z
------------------------- run concurrently ----------------------
<ubuntu system> <fedora system> <debian system> <rhel6 system>
mkdir ubuntu mkdir fedora mkdir debian mkdir rhel6
cd ubuntu cd fedora cd debian cd rhel6
../configure ../configure ../configure ../configure
make make make make
make check make check make check make check
This change also moves many of the include headers from individual
incude/sys directories under the modules directory in to a single
top level include directory. This has the advantage of making
the build rules cleaner and logically it makes a bit more sense.
Jason Lee
Rob Norris
Richard Yao
Tino Reichardt
наб
Michael Niewöhner
Matthew Ahrens
David Quigley
Dan Kimmel
Will Andrews
Richard Yao
Richard Yao
Eric Dillmann
Brian Behlendorf