Pull block fixes from Jens Axboe:
"Small set of fixes that should go into this series. This contains:
- compat signal mask fix for io_uring (Arnd)
- EAGAIN corner case for direct vs buffered writes for io_uring
(Roman)
- NVMe pull request from Christoph with various little fixes
- sbitmap ws_active fix, which caused a perf regression for shared
tags (me)
- sbitmap bit ordering fix (Ming)
- libata on-stack DMA fix (Raymond)"
* tag 'for-linus-20190329' of git://git.kernel.dk/linux-block:
nvmet: fix error flow during ns enable
nvmet: fix building bvec from sg list
nvme-multipath: relax ANA state check
nvme-tcp: fix an endianess miss-annotation
libata: fix using DMA buffers on stack
io_uring: offload write to async worker in case of -EAGAIN
sbitmap: order READ/WRITE freed instance and setting clear bit
blk-mq: fix sbitmap ws_active for shared tags
io_uring: fix big-endian compat signal mask handling
blk-mq: update comment for blk_mq_hctx_has_pending()
blk-mq: use blk_mq_put_driver_tag() to put tag
Pull networking fixes from David Miller:
"Fixes here and there, a couple new device IDs, as usual:
1) Fix BQL race in dpaa2-eth driver, from Ioana Ciornei.
2) Fix 64-bit division in iwlwifi, from Arnd Bergmann.
3) Fix documentation for some eBPF helpers, from Quentin Monnet.
4) Some UAPI bpf header sync with tools, also from Quentin Monnet.
5) Set descriptor ownership bit at the right time for jumbo frames in
stmmac driver, from Aaro Koskinen.
6) Set IFF_UP properly in tun driver, from Eric Dumazet.
7) Fix load/store doubleword instruction generation in powerpc eBPF
JIT, from Naveen N. Rao.
8) nla_nest_start() return value checks all over, from Kangjie Lu.
9) Fix asoc_id handling in SCTP after the SCTP_*_ASSOC changes this
merge window. From Marcelo Ricardo Leitner and Xin Long.
10) Fix memory corruption with large MTUs in stmmac, from Aaro
Koskinen.
11) Do not use ipv4 header for ipv6 flows in TCP and DCCP, from Eric
Dumazet.
12) Fix topology subscription cancellation in tipc, from Erik Hugne.
13) Memory leak in genetlink error path, from Yue Haibing.
14) Valid control actions properly in packet scheduler, from Davide
Caratti.
15) Even if we get EEXIST, we still need to rehash if a shrink was
delayed. From Herbert Xu.
16) Fix interrupt mask handling in interrupt handler of r8169, from
Heiner Kallweit.
17) Fix leak in ehea driver, from Wen Yang"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (168 commits)
dpaa2-eth: fix race condition with bql frame accounting
chelsio: use BUG() instead of BUG_ON(1)
net: devlink: skip info_get op call if it is not defined in dumpit
net: phy: bcm54xx: Encode link speed and activity into LEDs
tipc: change to check tipc_own_id to return in tipc_net_stop
net: usb: aqc111: Extend HWID table by QNAP device
net: sched: Kconfig: update reference link for PIE
net: dsa: qca8k: extend slave-bus implementations
net: dsa: qca8k: remove leftover phy accessors
dt-bindings: net: dsa: qca8k: support internal mdio-bus
dt-bindings: net: dsa: qca8k: fix example
net: phy: don't clear BMCR in genphy_soft_reset
bpf, libbpf: clarify bump in libbpf version info
bpf, libbpf: fix version info and add it to shared object
rxrpc: avoid clang -Wuninitialized warning
tipc: tipc clang warning
net: sched: fix cleanup NULL pointer exception in act_mirr
r8169: fix cable re-plugging issue
net: ethernet: ti: fix possible object reference leak
net: ibm: fix possible object reference leak
...
As it stands if a shrink is delayed because of an outstanding
rehash, we will go into a rescheduling loop without ever doing
the rehash.
This patch fixes this by still carrying out the rehash and then
rescheduling so that we can shrink after the completion of the
rehash should it still be necessary.
The return value of EEXIST captures this case and other cases
(e.g., another thread expanded/rehashed the table at the same
time) where we should still proceed with the rehash.
Fixes: da20420f83 ("rhashtable: Add nested tables")
Reported-by: Josh Elsasser <jelsasser@appneta.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Josh Elsasser <jelsasser@appneta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull more Kbuild updates from Masahiro Yamada:
- add more Build-Depends to Debian source package
- prefix header search paths with $(srctree)/
- make modpost show verbose section mismatch warnings
- avoid hard-coded CROSS_COMPILE for h8300
- fix regression for Debian make-kpkg command
- add semantic patch to detect missing put_device()
- fix some warnings of 'make deb-pkg'
- optimize NOSTDINC_FLAGS evaluation
- add warnings about redundant generic-y
- clean up Makefiles and scripts
* tag 'kbuild-v5.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kconfig: remove stale lxdialog/.gitignore
kbuild: force all architectures except um to include mandatory-y
kbuild: warn redundant generic-y
Revert "modsign: Abort modules_install when signing fails"
kbuild: Make NOSTDINC_FLAGS a simply expanded variable
kbuild: deb-pkg: avoid implicit effects
coccinelle: semantic code search for missing put_device()
kbuild: pkg: grep include/config/auto.conf instead of $KCONFIG_CONFIG
kbuild: deb-pkg: introduce is_enabled and if_enabled_echo to builddeb
kbuild: deb-pkg: add CONFIG_ prefix to kernel config options
kbuild: add workaround for Debian make-kpkg
kbuild: source include/config/auto.conf instead of ${KCONFIG_CONFIG}
unicore32: simplify linker script generation for decompressor
h8300: use cc-cross-prefix instead of hardcoding h8300-unknown-linux-
kbuild: move archive command to scripts/Makefile.lib
modpost: always show verbose warning for section mismatch
ia64: prefix header search path with $(srctree)/
libfdt: prefix header search paths with $(srctree)/
deb-pkg: generate correct build dependencies
Pull ARM updates from Russell King:
- An improvement from Ard Biesheuvel, who noted that the identity map
setup was taking a long time due to flush_cache_louis().
- Update a comment about dma_ops from Wolfram Sang.
- Remove use of "-p" with ld, where this flag has been a no-op since
2004.
- Remove the printing of the virtual memory layout, which is no longer
useful since we hide pointers.
- Correct SCU help text.
- Remove legacy TWD registration method.
- Add pgprot_device() implementation for mapping PCI sysfs resource
files.
- Initialise PFN limits earlier for kmemleak.
- Fix argument count to match macro definition (affects clang builds)
- Use unified assembler language almost everywhere for clang, and other
clang improvements (from Stefan Agner, Nathan Chancellor).
- Support security extension for noMMU and other noMMU cleanups (from
Vladimir Murzin).
- Remove unnecessary SMP bringup code (which was incorrectly copy'n'
pasted from the ARM platform implementations) and remove it from the
arch code to discourge further copys of it appearing.
- Add Cortex A9 erratum preventing kexec working on some SoCs.
- AMBA bus identification updates from Mike Leach.
- More use of raw spinlocks to avoid -RT kernel issues (from Yang Shi
and Sebastian Andrzej Siewior).
- MCPM hyp/svc mode mismatch fixes from Marek Szyprowski.
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: (32 commits)
ARM: 8849/1: NOMMU: Fix encodings for PMSAv8's PRBAR4/PRLAR4
ARM: 8848/1: virt: Align GIC version check with arm64 counterpart
ARM: 8847/1: pm: fix HYP/SVC mode mismatch when MCPM is used
ARM: 8845/1: use unified assembler in c files
ARM: 8844/1: use unified assembler in assembly files
ARM: 8843/1: use unified assembler in headers
ARM: 8841/1: use unified assembler in macros
ARM: 8840/1: use a raw_spinlock_t in unwind
ARM: 8839/1: kprobe: make patch_lock a raw_spinlock_t
ARM: 8837/1: coresight: etmv4: Update ID register table to add UCI support
ARM: 8836/1: drivers: amba: Update component matching to use the CoreSight UCI values.
ARM: 8838/1: drivers: amba: Updates to component identification for driver matching.
ARM: 8833/1: Ensure that NEON code always compiles with Clang
ARM: avoid Cortex-A9 livelock on tight dmb loops
ARM: smp: remove arch-provided "pen_release"
ARM: actions: remove boot_lock and pen_release
ARM: oxnas: remove CPU hotplug implementation
ARM: qcom: remove unnecessary boot_lock
ARM: 8832/1: NOMMU: Limit visibility for CONFIG_FLASH_{MEM_BASE,SIZE}
ARM: 8831/1: NOMMU: pmsa-v8: remove unneeded semicolon
...
Currently, the Kbuild core manipulates header search paths in a crazy
way [1].
To fix this mess, I want all Makefiles to add explicit $(srctree)/ to
the search paths in the srctree. Some Makefiles are already written in
that way, but not all. The goal of this work is to make the notation
consistent, and finally get rid of the gross hacks.
Having whitespaces after -I does not matter since commit 48f6e3cf5b
("kbuild: do not drop -I without parameter").
[1]: https://patchwork.kernel.org/patch/9632347/
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Pull iov_iter updates from Al Viro:
"A couple of iov_iter patches - Christoph's crapectomy (the last
remaining user of iov_for_each() went away with lustre, IIRC) and
Eric'c optimization of sanity checks"
* 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
iov_iter: optimize page_copy_sane()
uio: remove the unused iov_for_each macro
Merge misc updates from Andrew Morton:
- a few misc things
- the rest of MM
- remove flex_arrays, replace with new simple radix-tree implementation
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (38 commits)
Drop flex_arrays
sctp: convert to genradix
proc: commit to genradix
generic radix trees
selinux: convert to kvmalloc
md: convert to kvmalloc
openvswitch: convert to kvmalloc
of: fix kmemleak crash caused by imbalance in early memory reservation
mm: memblock: update comments and kernel-doc
memblock: split checks whether a region should be skipped to a helper function
memblock: remove memblock_{set,clear}_region_flags
memblock: drop memblock_alloc_*_nopanic() variants
memblock: memblock_alloc_try_nid: don't panic
treewide: add checks for the return value of memblock_alloc*()
swiotlb: add checks for the return value of memblock_alloc*()
init/main: add checks for the return value of memblock_alloc*()
mm/percpu: add checks for the return value of memblock_alloc*()
sparc: add checks for the return value of memblock_alloc*()
ia64: add checks for the return value of memblock_alloc*()
arch: don't memset(0) memory returned by memblock_alloc()
...
Pull XArray updates from Matthew Wilcox:
"This pull request changes the xa_alloc() API. I'm only aware of one
subsystem that has started trying to use it, and we agree on the fixup
as part of the merge.
The xa_insert() error code also changed to match xa_alloc() (EEXIST to
EBUSY), and I added xa_alloc_cyclic(). Beyond that, the usual
bugfixes, optimisations and tweaking.
I now have a git tree with all users of the radix tree and IDR
converted over to the XArray that I'll be feeding to maintainers over
the next few weeks"
* tag 'xarray-5.1-rc1' of git://git.infradead.org/users/willy/linux-dax:
XArray: Fix xa_reserve for 2-byte aligned entries
XArray: Fix xa_erase of 2-byte aligned entries
XArray: Use xa_cmpxchg to implement xa_reserve
XArray: Fix xa_release in allocating arrays
XArray: Mark xa_insert and xa_reserve as must_check
XArray: Add cyclic allocation
XArray: Redesign xa_alloc API
XArray: Add support for 1s-based allocation
XArray: Change xa_insert to return -EBUSY
XArray: Update xa_erase family descriptions
XArray tests: RCU lock prohibits GFP_KERNEL
Pull Kbuild updates from Masahiro Yamada:
- do not generate unneeded top-level built-in.a
- let git ignore O= directory entirely
- optimize scripts/kallsyms slightly
- exclude DWARF info from *.s regardless of config options
- fix GCC toolchain search path for Clang to prepare ld.lld support
- do not generate modules.order when CONFIG_MODULES is disabled
- simplify single target rules and remove VPATH for external module
build
- allow to add optional flags to dpkg-buildpackage when building
deb-pkg
- move some compiler option tests from Makefile to Kconfig
- various Makefile cleanups
* tag 'kbuild-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (40 commits)
kbuild: remove scripts/basic/% build target
kbuild: use -Werror=implicit-... instead of -Werror-implicit-...
kbuild: clean up scripts/gcc-version.sh
kbuild: remove cc-version macro
kbuild: update comment block of scripts/clang-version.sh
kbuild: remove commented-out INITRD_COMPRESS
kbuild: move -gsplit-dwarf, -gdwarf-4 option tests to Kconfig
kbuild: [bin]deb-pkg: add DPKG_FLAGS variable
kbuild: move ".config not found!" message from Kconfig to Makefile
kbuild: invoke syncconfig if include/config/auto.conf.cmd is missing
kbuild: simplify single target rules
kbuild: remove empty rules for makefiles
kbuild: make -r/-R effective in top Makefile for old Make versions
kbuild: move tools_silent to a more relevant place
kbuild: compute false-positive -Wmaybe-uninitialized cases in Kconfig
kbuild: refactor cc-cross-prefix implementation
kbuild: hardcode genksyms path and remove GENKSYMS variable
scripts/gdb: refactor rules for symlink creation
kbuild: create symlink to vmlinux-gdb.py in scripts_gdb target
scripts/gdb: do not descend into scripts/gdb from scripts
...
Pull DMA mapping updates from Christoph Hellwig:
- add debugfs support for dumping dma-debug information (Corentin
Labbe)
- Kconfig cleanups (Andy Shevchenko and me)
- debugfs cleanups (Greg Kroah-Hartman)
- improve dma_map_resource and use it in the media code
- arch_setup_dma_ops / arch_teardown_dma_ops cleanups
- various small cleanups and improvements for the per-device coherent
allocator
- make the DMA mask an upper bound and don't fail "too large" dma mask
in the remaning two architectures - this will allow big driver
cleanups in the following merge windows
* tag 'dma-mapping-5.1' of git://git.infradead.org/users/hch/dma-mapping: (21 commits)
Documentation/DMA-API-HOWTO: update dma_mask sections
sparc64/pci_sun4v: allow large DMA masks
sparc64/iommu: allow large DMA masks
sparc64: refactor the ali DMA quirk
ccio: allow large DMA masks
dma-mapping: remove the DMA_MEMORY_EXCLUSIVE flag
dma-mapping: remove dma_mark_declared_memory_occupied
dma-mapping: move CONFIG_DMA_CMA to kernel/dma/Kconfig
dma-mapping: improve selection of dma_declare_coherent availability
dma-mapping: remove an incorrect __iommem annotation
of: select OF_RESERVED_MEM automatically
device.h: dma_mem is only needed for HAVE_GENERIC_DMA_COHERENT
mfd/sm501: depend on HAS_DMA
dma-mapping: add a kconfig symbol for arch_teardown_dma_ops availability
dma-mapping: add a kconfig symbol for arch_setup_dma_ops availability
dma-mapping: move debug configuration options to kernel/dma
dma-debug: add dumping facility via debugfs
dma: debug: no need to check return value of debugfs_create functions
videobuf2: replace a layering violation with dma_map_resource
dma-mapping: don't BUG when calling dma_map_resource on RAM
...
Pull arm64 updates from Catalin Marinas:
- Pseudo NMI support for arm64 using GICv3 interrupt priorities
- uaccess macros clean-up (unsafe user accessors also merged but
reverted, waiting for objtool support on arm64)
- ptrace regsets for Pointer Authentication (ARMv8.3) key management
- inX() ordering w.r.t. delay() on arm64 and riscv (acks in place by
the riscv maintainers)
- arm64/perf updates: PMU bindings converted to json-schema, unused
variable and misleading comment removed
- arm64/debug fixes to ensure checking of the triggering exception
level and to avoid the propagation of the UNKNOWN FAR value into the
si_code for debug signals
- Workaround for Fujitsu A64FX erratum 010001
- lib/raid6 ARM NEON optimisations
- NR_CPUS now defaults to 256 on arm64
- Minor clean-ups (documentation/comments, Kconfig warning, unused
asm-offsets, clang warnings)
- MAINTAINERS update for list information to the ARM64 ACPI entry
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (54 commits)
arm64: mmu: drop paging_init comments
arm64: debug: Ensure debug handlers check triggering exception level
arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals
Revert "arm64: uaccess: Implement unsafe accessors"
arm64: avoid clang warning about self-assignment
arm64: Kconfig.platforms: fix warning unmet direct dependencies
lib/raid6: arm: optimize away a mask operation in NEON recovery routine
lib/raid6: use vdupq_n_u8 to avoid endianness warnings
arm64: io: Hook up __io_par() for inX() ordering
riscv: io: Update __io_[p]ar() macros to take an argument
asm-generic/io: Pass result of I/O accessor to __io_[p]ar()
arm64: Add workaround for Fujitsu A64FX erratum 010001
arm64: Rename get_thread_info()
arm64: Remove documentation about TIF_USEDFPU
arm64: irqflags: Fix clang build warnings
arm64: Enable the support of pseudo-NMIs
arm64: Skip irqflags tracing for NMI in IRQs disabled context
arm64: Skip preemption when exiting an NMI
arm64: Handle serror in NMI context
irqchip/gic-v3: Allow interrupts to be set as pseudo-NMI
...
Pull rdma updates from Jason Gunthorpe:
"This has been a slightly more active cycle than normal with ongoing
core changes and quite a lot of collected driver updates.
- Various driver fixes for bnxt_re, cxgb4, hns, mlx5, pvrdma, rxe
- A new data transfer mode for HFI1 giving higher performance
- Significant functional and bug fix update to the mlx5
On-Demand-Paging MR feature
- A chip hang reset recovery system for hns
- Change mm->pinned_vm to an atomic64
- Update bnxt_re to support a new 57500 chip
- A sane netlink 'rdma link add' method for creating rxe devices and
fixing the various unregistration race conditions in rxe's
unregister flow
- Allow lookup up objects by an ID over netlink
- Various reworking of the core to driver interface:
- drivers should not assume umem SGLs are in PAGE_SIZE chunks
- ucontext is accessed via udata not other means
- start to make the core code responsible for object memory
allocation
- drivers should convert struct device to struct ib_device via a
helper
- drivers have more tools to avoid use after unregister problems"
* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (280 commits)
net/mlx5: ODP support for XRC transport is not enabled by default in FW
IB/hfi1: Close race condition on user context disable and close
RDMA/umem: Revert broken 'off by one' fix
RDMA/umem: minor bug fix in error handling path
RDMA/hns: Use GFP_ATOMIC in hns_roce_v2_modify_qp
cxgb4: kfree mhp after the debug print
IB/rdmavt: Fix concurrency panics in QP post_send and modify to error
IB/rdmavt: Fix loopback send with invalidate ordering
IB/iser: Fix dma_nents type definition
IB/mlx5: Set correct write permissions for implicit ODP MR
bnxt_re: Clean cq for kernel consumers only
RDMA/uverbs: Don't do double free of allocated PD
RDMA: Handle ucontext allocations by IB/core
RDMA/core: Fix a WARN() message
bnxt_re: fix the regression due to changes in alloc_pbl
IB/mlx4: Increase the timeout for CM cache
IB/core: Abort page fault handler silently during owning process exit
IB/mlx5: Validate correct PD before prefetch MR
IB/mlx5: Protect against prefetch of invalid MR
RDMA/uverbs: Store PR pointer before it is overwritten
...
Pull printk updates from Petr Mladek:
- Allow to sort mixed lines by an extra information about the caller
- Remove no longer used LOG_PREFIX.
- Some clean up and documentation update.
* tag 'printk-for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
printk/docs: Add extra integer types to printk-formats
printk: Remove no longer used LOG_PREFIX.
lib/vsprintf: Remove %pCr remnant in comment
printk: Pass caller information to log_store().
printk: Add caller information to printk() output.
Pull gcc-plugins updates from Kees Cook:
"This adds additional type coverage to the existing structleak plugin
and adds a large set of selftests to help evaluate stack variable
zero-initialization coverage.
That can be used to test whatever instrumentation might be performing
zero-initialization: either with the structleak plugin or with Clang's
coming "-ftrivial-auto-var-init=zero" option.
Summary:
- Add scalar and array initialization coverage
- Refactor Kconfig to make options more clear
- Add self-test module for testing automatic initialization"
* tag 'gcc-plugins-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
lib: Introduce test_stackinit module
gcc-plugins: structleak: Generalize to all variable types
Pull livepatching updates from Jiri Kosina:
- support for something we call 'atomic replace', and allows for much
better handling of cumulative patches (which is something very useful
for distros), from Jason Baron with help of Petr Mladek and Joe
Lawrence
- improvement of handling of tasks blocking finalization, from Miroslav
Benes
- update of MAINTAINERS file to reflect move towards group
maintainership
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching: (22 commits)
livepatch/selftests: use "$@" to preserve argument list
livepatch: Module coming and going callbacks can proceed with all listed patches
livepatch: Proper error handling in the shadow variables selftest
livepatch: return -ENOMEM on ptr_id() allocation failure
livepatch: Introduce klp_for_each_patch macro
livepatch: core: Return EOPNOTSUPP instead of ENOSYS
selftests/livepatch: add DYNAMIC_DEBUG config dependency
livepatch: samples: non static warnings fix
livepatch: update MAINTAINERS
livepatch: Remove signal sysfs attribute
livepatch: Send a fake signal periodically
selftests/livepatch: introduce tests
livepatch: Remove ordering (stacking) of the livepatches
livepatch: Atomic replace and cumulative patches documentation
livepatch: Remove Nop structures when unused
livepatch: Add atomic replace
livepatch: Use lists to manage patches, objects and functions
livepatch: Simplify API by removing registration step
livepatch: Don't block the removal of patches loaded after a forced transition
livepatch: Consolidate klp_free functions
...
Patch series "lib/lzo: run-length encoding support", v5.
Following on from the previous lzo-rle patchset:
https://lkml.org/lkml/2018/11/30/972
This patchset contains only the RLE patches, and should be applied on
top of the non-RLE patches ( https://lkml.org/lkml/2019/2/5/366 ).
Previously, some questions were raised around the RLE patches. I've
done some additional benchmarking to answer these questions. In short:
- RLE offers significant additional performance (data-dependent)
- I didn't measure any regressions that were clearly outside the noise
One concern with this patchset was around performance - specifically,
measuring RLE impact separately from Matt Sealey's patches (CTZ & fast
copy). I have done some additional benchmarking which I hope clarifies
the benefits of each part of the patchset.
Firstly, I've captured some memory via /dev/fmem from a Chromebook with
many tabs open which is starting to swap, and then split this into 4178
4k pages. I've excluded the all-zero pages (as zram does), and also the
no-zero pages (which won't tell us anything about RLE performance).
This should give a realistic test dataset for zram. What I found was
that the data is VERY bimodal: 44% of pages in this dataset contain 5%
or fewer zeros, and 44% contain over 90% zeros (30% if you include the
no-zero pages). This supports the idea of special-casing zeros in zram.
Next, I've benchmarked four variants of lzo on these pages (on 64-bit
Arm at max frequency): baseline LZO; baseline + Matt Sealey's patches
(aka MS); baseline + RLE only; baseline + MS + RLE. Numbers are for
weighted roundtrip throughput (the weighting reflects that zram does
more compression than decompression).
https://drive.google.com/file/d/1VLtLjRVxgUNuWFOxaGPwJYhl_hMQXpHe/view?usp=sharing
Matt's patches help in all cases for Arm (and no effect on Intel), as
expected.
RLE also behaves as expected: with few zeros present, it makes no
difference; above ~75%, it gives a good improvement (50 - 300 MB/s on
top of the benefit from Matt's patches).
Best performance is seen with both MS and RLE patches.
Finally, I have benchmarked the same dataset on an x86-64 device. Here,
the MS patches make no difference (as expected); RLE helps, similarly as
on Arm. There were no definite regressions; allowing for observational
error, 0.1% (3/4178) of cases had a regression > 1 standard deviation,
of which the largest was 4.6% (1.2 standard deviations). I think this
is probably within the noise.
https://drive.google.com/file/d/1xCUVwmiGD0heEMx5gcVEmLBI4eLaageV/view?usp=sharing
One point to note is that the graphs show RLE appears to help very
slightly with no zeros present! This is because the extra code causes
the clang optimiser to change code layout in a way that happens to have
a significant benefit. Taking baseline LZO and adding a do-nothing line
like "__builtin_prefetch(out_len);" immediately before the "goto next"
has the same effect. So this is a real, but basically spurious effect -
it's small enough not to upset the overall findings.
This patch (of 3):
When using zram, we frequently encounter long runs of zero bytes. This
adds a special case which identifies runs of zeros and encodes them
using run-length encoding.
This is faster for both compression and decompresion. For high-entropy
data which doesn't hit this case, impact is minimal.
Compression ratio is within a few percent in all cases.
This modifies the bitstream in a way which is backwards compatible
(i.e., we can decompress old bitstreams, but old versions of lzo cannot
decompress new bitstreams).
Link: http://lkml.kernel.org/r/20190205155944.16007-2-dave.rodgman@arm.com
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Markus F.X.J. Oberhumer <markus@oberhumer.com>
Cc: Matt Sealey <matt.sealey@arm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <nitingupta910@gmail.com>
Cc: Richard Purdie <rpurdie@openedhand.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Sonny Rao <sonnyrao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
