From 3337d5cfe5e08f7ee70f63dc189c6e0b9dd8b8bf Mon Sep 17 00:00:00 2001 From: Alexey Brodkin Date: Thu, 7 Mar 2019 16:29:50 -0800 Subject: configs: get rid of obsolete CONFIG_ENABLE_WARN_DEPRECATED This Kconfig option was removed during v4.19 development in commit 771c035372a0 ("deprecate the '__deprecated' attribute warnings entirely and for good") so there's no point to keep it in defconfigs any longer. FWIW defconfigs were patched with: --------------------------->8---------------------- find . -name *_defconfig -exec sed -i '/CONFIG_ENABLE_WARN_DEPRECATED/d' {} \; --------------------------->8---------------------- Link: http://lkml.kernel.org/r/20190128152434.41969-1-abrodkin@synopsys.com Signed-off-by: Alexey Brodkin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/process/4.Coding.rst | 2 +- Documentation/translations/it_IT/process/4.Coding.rst | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'Documentation') diff --git a/Documentation/process/4.Coding.rst b/Documentation/process/4.Coding.rst index cfe264889447..4b7a5ab3cec1 100644 --- a/Documentation/process/4.Coding.rst +++ b/Documentation/process/4.Coding.rst @@ -249,7 +249,7 @@ features; most of these are found in the "kernel hacking" submenu. Several of these options should be turned on for any kernel used for development or testing purposes. In particular, you should turn on: - - ENABLE_WARN_DEPRECATED, ENABLE_MUST_CHECK, and FRAME_WARN to get an + - ENABLE_MUST_CHECK and FRAME_WARN to get an extra set of warnings for problems like the use of deprecated interfaces or ignoring an important return value from a function. The output generated by these warnings can be verbose, but one need not worry about diff --git a/Documentation/translations/it_IT/process/4.Coding.rst b/Documentation/translations/it_IT/process/4.Coding.rst index c61059015e52..c05b89e616dd 100644 --- a/Documentation/translations/it_IT/process/4.Coding.rst +++ b/Documentation/translations/it_IT/process/4.Coding.rst @@ -264,7 +264,7 @@ La maggior parte di queste opzioni possono essere attivate per qualsiasi kernel utilizzato per lo sviluppo o a scopo di test. In particolare dovreste attivare: - - ENABLE_WARN_DEPRECATED, ENABLE_MUST_CHECK, e FRAME_WARN per ottenere degli + - ENABLE_MUST_CHECK e FRAME_WARN per ottenere degli avvertimenti dedicati a problemi come l'uso di interfacce deprecate o l'ignorare un importante valore di ritorno di una funzione. Il risultato generato da questi avvertimenti può risultare verboso, ma non bisogna -- cgit v1.2.3 From 13610aa908dcfce77135bb799c0a10d0172da6ba Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 7 Mar 2019 16:29:53 -0800 Subject: kernel/configs: use .incbin directive to embed config_data.gz This slightly optimizes the kernel/configs.c build. bin2c is not very efficient because it converts a data file into a huge array to embed it into a *.c file. Instead, we can use the .incbin directive. Also, this simplifies the code; Makefile is cleaner, and the way to get the offset/size of the config_data.gz is more straightforward. I used the "asm" statement in *.c instead of splitting it into *.S because MODULE_* tags are not supported in *.S files. I also cleaned up kernel/.gitignore; "config_data.gz" is unneeded because the top-level .gitignore takes care of the "*.gz" pattern. [yamada.masahiro@socionext.com: v2] Link: http://lkml.kernel.org/r/1550108893-21226-1-git-send-email-yamada.masahiro@socionext.com Link: http://lkml.kernel.org/r/1549941160-8084-1-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Masahiro Yamada Cc: Randy Dunlap Cc: Arnd Bergmann Cc: Alexander Popov Cc: Kees Cook Cc: Jonathan Corbet Cc: Thomas Gleixner Cc: Dan Williams Cc: Mathieu Desnoyers Cc: Richard Guy Briggs Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/dontdiff | 1 - 1 file changed, 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/dontdiff b/Documentation/dontdiff index 2228fcc8e29f..ef25a066d952 100644 --- a/Documentation/dontdiff +++ b/Documentation/dontdiff @@ -106,7 +106,6 @@ compile.h* conf config config-* -config_data.h* config.mak config.mak.autogen conmakehash -- cgit v1.2.3 From 5ee4014af99f77dac89e01961b717d13ff1a8ea5 Mon Sep 17 00:00:00 2001 From: Dave Rodgman Date: Thu, 7 Mar 2019 16:30:40 -0800 Subject: lib/lzo: implement run-length encoding 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 Cc: David S. Miller Cc: Greg Kroah-Hartman Cc: Herbert Xu Cc: Markus F.X.J. Oberhumer Cc: Matt Sealey Cc: Minchan Kim Cc: Nitin Gupta Cc: Richard Purdie Cc: Sergey Senozhatsky Cc: Sonny Rao Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/lzo.txt | 35 ++++++++++++++++++++++++++++------- 1 file changed, 28 insertions(+), 7 deletions(-) (limited to 'Documentation') diff --git a/Documentation/lzo.txt b/Documentation/lzo.txt index 6fa6a93d0949..306c60344ca7 100644 --- a/Documentation/lzo.txt +++ b/Documentation/lzo.txt @@ -78,16 +78,30 @@ Description is an implementation design choice independent on the algorithm or encoding. +Versions + +0: Original version +1: LZO-RLE + +Version 1 of LZO implements an extension to encode runs of zeros using run +length encoding. This improves speed for data with many zeros, which is a +common case for zram. This modifies the bitstream in a backwards compatible way +(v1 can correctly decompress v0 compressed data, but v0 cannot read v1 data). + Byte sequences ============== First byte encoding:: - 0..17 : follow regular instruction encoding, see below. It is worth - noting that codes 16 and 17 will represent a block copy from - the dictionary which is empty, and that they will always be + 0..16 : follow regular instruction encoding, see below. It is worth + noting that code 16 will represent a block copy from the + dictionary which is empty, and that it will always be invalid at this place. + 17 : bitstream version. If the first byte is 17, the next byte + gives the bitstream version. If the first byte is not 17, + the bitstream version is 0. + 18..21 : copy 0..3 literals state = (byte - 17) = 0..3 [ copy literals ] skip byte @@ -140,6 +154,11 @@ Byte sequences state = S (copy S literals after this block) End of stream is reached if distance == 16384 + In version 1, this instruction is also used to encode a run of zeros if + distance = 0xbfff, i.e. H = 1 and the D bits are all 1. + In this case, it is followed by a fourth byte, X. + run length = ((X << 3) | (0 0 0 0 0 L L L)) + 4. + 0 0 1 L L L L L (32..63) Copy of small block within 16kB distance (preferably less than 34B) length = 2 + (L ?: 31 + (zero_bytes * 255) + non_zero_byte) @@ -165,7 +184,9 @@ Authors ======= This document was written by Willy Tarreau on 2014/07/19 during an - analysis of the decompression code available in Linux 3.16-rc5. The code is - tricky, it is possible that this document contains mistakes or that a few - corner cases were overlooked. In any case, please report any doubt, fix, or - proposed updates to the author(s) so that the document can be updated. + analysis of the decompression code available in Linux 3.16-rc5, and updated + by Dave Rodgman on 2018/10/30 to introduce run-length + encoding. The code is tricky, it is possible that this document contains + mistakes or that a few corner cases were overlooked. In any case, please + report any doubt, fix, or proposed updates to the author(s) so that the + document can be updated. -- cgit v1.2.3 From 45ec975efb527625629d123f30597673889f52ca Mon Sep 17 00:00:00 2001 From: Dave Rodgman Date: Thu, 7 Mar 2019 16:30:44 -0800 Subject: lib/lzo: separate lzo-rle from lzo To prevent any issues with persistent data, separate lzo-rle from lzo so that it is treated as a separate algorithm, and lzo is still available. Link: http://lkml.kernel.org/r/20190205155944.16007-3-dave.rodgman@arm.com Signed-off-by: Dave Rodgman Cc: David S. Miller Cc: Greg Kroah-Hartman Cc: Herbert Xu Cc: Markus F.X.J. Oberhumer Cc: Matt Sealey Cc: Minchan Kim Cc: Nitin Gupta Cc: Richard Purdie Cc: Sergey Senozhatsky Cc: Sonny Rao Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/lzo.txt | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'Documentation') diff --git a/Documentation/lzo.txt b/Documentation/lzo.txt index 306c60344ca7..f79934225d8d 100644 --- a/Documentation/lzo.txt +++ b/Documentation/lzo.txt @@ -88,6 +88,10 @@ length encoding. This improves speed for data with many zeros, which is a common case for zram. This modifies the bitstream in a backwards compatible way (v1 can correctly decompress v0 compressed data, but v0 cannot read v1 data). +For maximum compatibility, both versions are available under different names +(lzo and lzo-rle). Differences in the encoding are noted in this document with +e.g.: version 1 only. + Byte sequences ============== @@ -99,8 +103,8 @@ Byte sequences invalid at this place. 17 : bitstream version. If the first byte is 17, the next byte - gives the bitstream version. If the first byte is not 17, - the bitstream version is 0. + gives the bitstream version (version 1 only). If the first byte + is not 17, the bitstream version is 0. 18..21 : copy 0..3 literals state = (byte - 17) = 0..3 [ copy literals ] @@ -154,8 +158,8 @@ Byte sequences state = S (copy S literals after this block) End of stream is reached if distance == 16384 - In version 1, this instruction is also used to encode a run of zeros if - distance = 0xbfff, i.e. H = 1 and the D bits are all 1. + In version 1 only, this instruction is also used to encode a run of + zeros if distance = 0xbfff, i.e. H = 1 and the D bits are all 1. In this case, it is followed by a fourth byte, X. run length = ((X << 3) | (0 0 0 0 0 L L L)) + 4. -- cgit v1.2.3