- 15 5月, 2019 1 次提交
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由 George Spelvin 提交于
Patch series "lib/sort & lib/list_sort: faster and smaller", v2. Because CONFIG_RETPOLINE has made indirect calls much more expensive, I thought I'd try to reduce the number made by the library sort functions. The first three patches apply to lib/sort.c. Patch #1 is a simple optimization. The built-in swap has special cases for aligned 4- and 8-byte objects. But those are almost never used; most calls to sort() work on larger structures, which fall back to the byte-at-a-time loop. This generalizes them to aligned *multiples* of 4 and 8 bytes. (If nothing else, it saves an awful lot of energy by not thrashing the store buffers as much.) Patch #2 grabs a juicy piece of low-hanging fruit. I agree that nice simple solid heapsort is preferable to more complex algorithms (sorry, Andrey), but it's possible to implement heapsort with far fewer comparisons (50% asymptotically, 25-40% reduction for realistic sizes) than the way it's been done up to now. And with some care, the code ends up smaller, as well. This is the "big win" patch. Patch #3 adds the same sort of indirect call bypass that has been added to the net code of late. The great majority of the callers use the builtin swap functions, so replace the indirect call to sort_func with a (highly preditable) series of if() statements. Rather surprisingly, this decreased code size, as the swap functions were inlined and their prologue & epilogue code eliminated. lib/list_sort.c is a bit trickier, as merge sort is already close to optimal, and we don't want to introduce triumphs of theory over practicality like the Ford-Johnson merge-insertion sort. Patch #4, without changing the algorithm, chops 32% off the code size and removes the part[MAX_LIST_LENGTH+1] pointer array (and the corresponding upper limit on efficiently sortable input size). Patch #5 improves the algorithm. The previous code is already optimal for power-of-two (or slightly smaller) size inputs, but when the input size is just over a power of 2, there's a very unbalanced final merge. There are, in the literature, several algorithms which solve this, but they all depend on the "breadth-first" merge order which was replaced by commit 835cc0c8 with a more cache-friendly "depth-first" order. Some hard thinking came up with a depth-first algorithm which defers merges as little as possible while avoiding bad merges. This saves 0.2*n compares, averaged over all sizes. The code size increase is minimal (64 bytes on x86-64, reducing the net savings to 26%), but the comments expanded significantly to document the clever algorithm. TESTING NOTES: I have some ugly user-space benchmarking code which I used for testing before moving this code into the kernel. Shout if you want a copy. I'm running this code right now, with CONFIG_TEST_SORT and CONFIG_TEST_LIST_SORT, but I confess I haven't rebooted since the last round of minor edits to quell checkpatch. I figure there will be at least one round of comments and final testing. This patch (of 5): Rather than having special-case swap functions for 4- and 8-byte objects, special-case aligned multiples of 4 or 8 bytes. This speeds up most users of sort() by avoiding fallback to the byte copy loop. Despite what ca96ab85 ("lib/sort: Add 64 bit swap function") claims, very few users of sort() sort pointers (or pointer-sized objects); most sort structures containing at least two words. (E.g. drivers/acpi/fan.c:acpi_fan_get_fps() sorts an array of 40-byte struct acpi_fan_fps.) The functions also got renamed to reflect the fact that they support multiple words. In the great tradition of bikeshedding, the names were by far the most contentious issue during review of this patch series. x86-64 code size 872 -> 886 bytes (+14) With feedback from Andy Shevchenko, Rasmus Villemoes and Geert Uytterhoeven. Link: http://lkml.kernel.org/r/f24f932df3a7fa1973c1084154f1cea596bcf341.1552704200.git.lkml@sdf.orgSigned-off-by: NGeorge Spelvin <lkml@sdf.org> Acked-by: NAndrey Abramov <st5pub@yandex.ru> Acked-by: NRasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Daniel Wagner <daniel.wagner@siemens.com> Cc: Don Mullis <don.mullis@gmail.com> Cc: Dave Chinner <dchinner@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 02 11月, 2017 1 次提交
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由 Greg Kroah-Hartman 提交于
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: NKate Stewart <kstewart@linuxfoundation.org> Reviewed-by: NPhilippe Ombredanne <pombredanne@nexb.com> Reviewed-by: NThomas Gleixner <tglx@linutronix.de> Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
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- 25 2月, 2017 1 次提交
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由 Kostenzer Felix 提交于
Along with the addition made to Kconfig.debug, the prior existing but permanently disabled test function has been slightly refactored. Patch has been tested using QEMU 2.1.2 with a .config obtained through 'make defconfig' (x86_64) and manually enabling the option. [arnd@arndb.de: move sort self-test into a separate file] Link: http://lkml.kernel.org/r/20170112110657.3123790-1-arnd@arndb.de Link: http://lkml.kernel.org/r/HE1PR09MB0394B0418D504DCD27167D4FD49B0@HE1PR09MB0394.eurprd09.prod.outlook.comSigned-off-by: NKostenzer Felix <fkostenzer@live.at> Signed-off-by: NArnd Bergmann <arnd@arndb.de> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 26 6月, 2015 1 次提交
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由 Daniel Wagner 提交于
In case the call side is not providing a swap function, we either use a 32 bit or a generic swap function. When swapping around pointers on 64 bit architectures falling back to use the generic swap function seems like an unnecessary waste. There at least 9 users ('sort' is of difficult to grep for) of sort() and all of them use the sort function without a customized swap function. Furthermore, they are all using pointers to swap around: arch/x86/kernel/e820.c:sanitize_e820_map() arch/x86/mm/extable.c:sort_extable() drivers/acpi/fan.c:acpi_fan_get_fps() fs/btrfs/super.c:btrfs_descending_sort_devices() fs/xfs/libxfs/xfs_dir2_block.c:xfs_dir2_sf_to_block() kernel/range.c:clean_sort_range() mm/memcontrol.c:__mem_cgroup_usage_register_event() sound/pci/hda/hda_auto_parser.c:snd_hda_parse_pin_defcfg() sound/pci/hda/hda_auto_parser.c:sort_pins_by_sequence() Obviously, we could improve the swap for other sizes as well but this is overkill at this point. A simple test shows sorting a 400 element array (try to stay in one page) with either with u32_swap() or u64_swap() show that the theory actually works. This test was done on a x86_64 (Intel Xeon E5-4610) machine. - swap_32: NumSamples = 100; Min = 48.00; Max = 49.00 Mean = 48.320000; Variance = 0.217600; SD = 0.466476; Median 48.000000 each * represents a count of 1 48.0000 - 48.1000 [ 68]: ******************************************************************** 48.1000 - 48.2000 [ 0]: 48.2000 - 48.3000 [ 0]: 48.3000 - 48.4000 [ 0]: 48.4000 - 48.5000 [ 0]: 48.5000 - 48.6000 [ 0]: 48.6000 - 48.7000 [ 0]: 48.7000 - 48.8000 [ 0]: 48.8000 - 48.9000 [ 0]: 48.9000 - 49.0000 [ 32]: ******************************** - swap_64: NumSamples = 100; Min = 44.00; Max = 63.00 Mean = 48.250000; Variance = 18.687500; SD = 4.322904; Median 47.000000 each * represents a count of 1 44.0000 - 45.9000 [ 15]: *************** 45.9000 - 47.8000 [ 37]: ************************************* 47.8000 - 49.7000 [ 39]: *************************************** 49.7000 - 51.6000 [ 0]: 51.6000 - 53.5000 [ 0]: 53.5000 - 55.4000 [ 0]: 55.4000 - 57.3000 [ 0]: 57.3000 - 59.2000 [ 1]: * 59.2000 - 61.1000 [ 3]: *** 61.1000 - 63.0000 [ 5]: ***** - swap_72: NumSamples = 100; Min = 53.00; Max = 71.00 Mean = 55.070000; Variance = 21.565100; SD = 4.643824; Median 53.000000 each * represents a count of 1 53.0000 - 54.8000 [ 73]: ************************************************************************* 54.8000 - 56.6000 [ 9]: ********* 56.6000 - 58.4000 [ 9]: ********* 58.4000 - 60.2000 [ 0]: 60.2000 - 62.0000 [ 0]: 62.0000 - 63.8000 [ 0]: 63.8000 - 65.6000 [ 0]: 65.6000 - 67.4000 [ 1]: * 67.4000 - 69.2000 [ 4]: **** 69.2000 - 71.0000 [ 4]: **** - test program: static int cmp_32(const void *a, const void *b) { u32 l = *(u32 *)a; u32 r = *(u32 *)b; if (l < r) return -1; if (l > r) return 1; return 0; } static int cmp_64(const void *a, const void *b) { u64 l = *(u64 *)a; u64 r = *(u64 *)b; if (l < r) return -1; if (l > r) return 1; return 0; } static int cmp_72(const void *a, const void *b) { u32 l = get_unaligned((u32 *) a); u32 r = get_unaligned((u32 *) b); if (l < r) return -1; if (l > r) return 1; return 0; } static void init_array32(void *array) { u32 *a = array; int i; a[0] = 3821; for (i = 1; i < ARRAY_ELEMENTS; i++) a[i] = next_pseudo_random32(a[i-1]); } static void init_array64(void *array) { u64 *a = array; int i; a[0] = 3821; for (i = 1; i < ARRAY_ELEMENTS; i++) a[i] = next_pseudo_random32(a[i-1]); } static void init_array72(void *array) { char *p; u32 v; int i; v = 3821; for (i = 0; i < ARRAY_ELEMENTS; i++) { p = (char *)array + (i * 9); put_unaligned(v, (u32*) p); v = next_pseudo_random32(v); } } static void sort_test(void (*init)(void *array), int (*cmp) (const void *, const void *), void *array, size_t size) { ktime_t start, stop; int i; for (i = 0; i < 10000; i++) { init(array); local_irq_disable(); start = ktime_get(); sort(array, ARRAY_ELEMENTS, size, cmp, NULL); stop = ktime_get(); local_irq_enable(); if (i > 10000 - 101) pr_info("%lld\n", ktime_to_us(ktime_sub(stop, start))); } } static void *create_array(size_t size) { void *array; array = kmalloc(ARRAY_ELEMENTS * size, GFP_KERNEL); if (!array) return NULL; return array; } static int perform_test(size_t size) { void *array; array = create_array(size); if (!array) return -ENOMEM; pr_info("test element size %d bytes\n", (int)size); switch (size) { case 4: sort_test(init_array32, cmp_32, array, size); break; case 8: sort_test(init_array64, cmp_64, array, size); break; case 9: sort_test(init_array72, cmp_72, array, size); break; } kfree(array); return 0; } static int __init sort_tests_init(void) { int err; err = perform_test(sizeof(u32)); if (err) return err; err = perform_test(sizeof(u64)); if (err) return err; err = perform_test(sizeof(u64)+1); if (err) return err; return 0; } static void __exit sort_tests_exit(void) { } module_init(sort_tests_init); module_exit(sort_tests_exit); MODULE_LICENSE("GPL v2"); MODULE_AUTHOR("Daniel Wagner"); MODULE_DESCRIPTION("sort perfomance tests"); Signed-off-by: NDaniel Wagner <daniel.wagner@bmw-carit.de> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 13 2月, 2015 2 次提交
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由 Rasmus Villemoes 提交于
The sort function and its helpers don't do memory allocation, so the slab.h include is redundant. Move it inside the #if 0 protecting the self-test, similar to how it is done in lib/list_sort.c. This removes over 450 lines from the generated dependency file. Signed-off-by: NRasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Rasmus Villemoes 提交于
sort.c doesn't use facilities from kernel.h, but does use some types defined in linux/types.h. Include the latter directly instead of relying on some other header doing it. Similarly, include linux/export.h directly instead of through module.h. This removes 80 lines from the dependency file .sort.o.cmd. Signed-off-by: NRasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 09 1月, 2009 1 次提交
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由 Wu Fengguang 提交于
This is to avoid name clashes for the introduction of a global swap() macro. Signed-off-by: NWu Fengguang <fengguang.wu@intel.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 17 10月, 2007 1 次提交
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由 Subbaiah Venkata 提交于
Hello, I fixed and tested a small bug in lib/sort.c file, heap sort function. The fix avoids unnecessary swap of contents when i is 0 (saves few loads and stores), which happens every time sort function is called. I felt the fix is worth bringing it to your attention given the importance and frequent use of the sort function. Acked-by: NMatt Mackall <mpm@selenic.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 12 2月, 2007 1 次提交
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由 Robert P. J. Day 提交于
A variety of (mostly) innocuous fixes to the embedded kernel-doc content in source files, including: * make multi-line initial descriptions single line * denote some function names, constants and structs as such * change erroneous opening '/*' to '/**' in a few places * reword some text for clarity Signed-off-by: NRobert P. J. Day <rpjday@mindspring.com> Cc: "Randy.Dunlap" <rdunlap@xenotime.net> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 03 10月, 2006 1 次提交
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由 keios 提交于
It is a non-standard heap-sort algorithm implementation because the index of child node is wrong . The sort function still outputs right result, but the performance is O( n * ( log(n) + 1 ) ) , about 10% ~ 20% worse than standard algorithm. Signed-off-by: Nkeios <keios.cn@gmail.com> Acked-by: NMatt Mackall <mpm@selenic.com> Acked-by: NZou Nan hai <nanhai.zou@intel.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 31 10月, 2005 1 次提交
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由 Tim Schmielau 提交于
I recently picked up my older work to remove unnecessary #includes of sched.h, starting from a patch by Dave Jones to not include sched.h from module.h. This reduces the number of indirect includes of sched.h by ~300. Another ~400 pointless direct includes can be removed after this disentangling (patch to follow later). However, quite a few indirect includes need to be fixed up for this. In order to feed the patches through -mm with as little disturbance as possible, I've split out the fixes I accumulated up to now (complete for i386 and x86_64, more archs to follow later) and post them before the real patch. This way this large part of the patch is kept simple with only adding #includes, and all hunks are independent of each other. So if any hunk rejects or gets in the way of other patches, just drop it. My scripts will pick it up again in the next round. Signed-off-by: NTim Schmielau <tim@physik3.uni-rostock.de> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 11 9月, 2005 1 次提交
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由 Adrian Bunk 提交于
This patch contains the following small cleanups: - make two needlessly global functions static - every file should #include the header files containing the prototypes of it's global functions Signed-off-by: NAdrian Bunk <bunk@stusta.de> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 06 5月, 2005 1 次提交
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由 Domen Puncer 提交于
The regression test in lib/sort.c is currently worthless because the array that is generated for sorting will be all zeros. This patch fixes things so that the array that is generated will contain unsorted integers (that are not all identical) as was probably intended. Signed-off-by Daniel Dickman <didickman@yahoo.com> Signed-off-by: NDomen Puncer <domen@coderock.org> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 17 4月, 2005 1 次提交
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由 Linus Torvalds 提交于
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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