linux/lib/vsprintf.c, branch v3.5

vsprintf: further optimize decimal conversion

2012-06-01T00:49:27Z

Previous code was using optimizations which were developed to work well even on narrow-word CPUs (by today's standards). But Linux runs only on 32-bit and wider CPUs. We can use that. First: using 32x32->64 multiply and trivial 32-bit shift, we can correctly divide by 10 much larger numbers, and thus we can print groups of 9 digits instead of groups of 5 digits. Next: there are two algorithms to print larger numbers. One is generic: divide by 1000000000 and repeatedly print groups of (up to) 9 digits. It's conceptually simple, but requires an (unsigned long long) / 1000000000 division. Second algorithm splits 64-bit unsigned long long into 16-bit chunks, manipulates them cleverly and generates groups of 4 decimal digits. It so happens that it does NOT require long long division. If long is > 32 bits, division of 64-bit values is relatively easy, and we will use the first algorithm. If long long is > 64 bits (strange architecture with VERY large long long), second algorithm can't be used, and we again use the first one. Else (if long is 32 bits and long long is 64 bits) we use second one. And third: there is a simple optimization which takes fast path not only for zero as was done before, but for all one-digit numbers. In all tested cases new code is faster than old one, in many cases by 30%, in few cases by more than 50% (for example, on x86-32, conversion of 12345678). Code growth is ~0 in 32-bit case and ~130 bytes in 64-bit case. This patch is based upon an original from Michal Nazarewicz. [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by: Michal Nazarewicz Signed-off-by: Denys Vlasenko Cc: Douglas W Jones Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

vsprintf: correctly handle width when '#' flag used in %#p format

2012-06-01T00:49:27Z

The '%p' output of the kernel's vsprintf() uses spec.field_width to determine how many digits to output based on 2 * sizeof(void*) so that all digits of a pointer are shown. ie. a pointer will be output as "001A2B3C" instead of "1A2B3C". However, if the '#' flag is used in the format (%#p), then the code doesn't take into account the width of the '0x' prefix and will end up outputing "0x1A2B3C" instead of "0x001A2B3C". This patch reworks the "pointer()" format hook to include 2 characters for the '0x' prefix if the '#' flag is included. [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by: Grant Likely Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/vsprintf.c: "%#o",0 becomes '0' instead of '00'

2012-05-29T23:22:33Z

number()'s behaviour is slighly changed: 0 becomes "0" instead of "00" when using the flag SPECIAL and base 8. Before: Number\Format %o %#o %x %#x 0 0 00 0 0x0 1 1 01 1 0x1 16 20 020 10 0x10 After: Number\Format %o %#o %x %#x 0 0 0 0 0x0 1 1 01 1 0x1 16 20 020 10 0x10 Signed-off-by: Pierre Carrier Acked-by: Stephen Rothwell Cc: Joe Perches Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

vsprintf: fix %ps on non symbols when using kallsyms

2012-05-29T23:22:32Z

Using %ps in a printk format will sometimes fail silently and print the empty string if the address passed in does not match a symbol that kallsyms knows about. But using %pS will fall back to printing the full address if kallsyms can't find the symbol. Make %ps act the same as %pS by falling back to printing the address. While we're here also make %ps print the module that a symbol comes from so that it matches what %pS already does. Take this simple function for example (in a module): static void test_printk(void) { int test; pr_info("with pS: %pS\n", &test); pr_info("with ps: %ps\n", &test); } Before this patch: with pS: 0xdff7df44 with ps: After this patch: with pS: 0xdff7df44 with ps: 0xdff7df44 Signed-off-by: Stephen Boyd Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'module-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux

2012-03-24T17:24:31Z

Pull cleanup of fs/ and lib/ users of module.h from Paul Gortmaker: "Fix up files in fs/ and lib/ dirs to only use module.h if they really need it. These are trivial in scope vs the work done previously. We now have things where any few remaining cleanups can be farmed out to arch or subsystem maintainers, and I have done so when possible. What is remaining here represents the bits that don't clearly lie within a single arch/subsystem boundary, like the fs dir and the lib dir. Some duplicate includes arising from overlapping fixes from independent subsystem maintainer submissions are also quashed." Fix up trivial conflicts due to clashes with other include file cleanups (including some due to the previous bug.h cleanup pull). * tag 'module-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux: lib: reduce the use of module.h wherever possible fs: reduce the use of module.h wherever possible includecheck: delete any duplicate instances of module.h

procfs: add num_to_str() to speed up /proc/stat

2012-03-23T23:58:42Z

== stat_check.py num = 0 with open("/proc/stat") as f: while num < 1000 : data = f.read() f.seek(0, 0) num = num + 1 == perf shows 20.39% stat_check.py [kernel.kallsyms] [k] format_decode 13.41% stat_check.py [kernel.kallsyms] [k] number 12.61% stat_check.py [kernel.kallsyms] [k] vsnprintf 10.85% stat_check.py [kernel.kallsyms] [k] memcpy 4.85% stat_check.py [kernel.kallsyms] [k] radix_tree_lookup 4.43% stat_check.py [kernel.kallsyms] [k] seq_printf This patch removes most of calls to vsnprintf() by adding num_to_str() and seq_print_decimal_ull(), which prints decimal numbers without rich functions provided by printf(). On my 8cpu box. == Before patch == [root@bluextal test]# time ./stat_check.py real 0m0.150s user 0m0.026s sys 0m0.121s == After patch == [root@bluextal test]# time ./stat_check.py real 0m0.055s user 0m0.022s sys 0m0.030s [akpm@linux-foundation.org: remove incorrect comment, use less statck in num_to_str(), move comment from .h to .c, simplify seq_put_decimal_ull()] [andrea@betterlinux.com: avoid breaking the ABI in /proc/stat] Signed-off-by: KAMEZAWA Hiroyuki Signed-off-by: Andrea Righi Cc: Eric Dumazet Cc: Glauber Costa Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Paul Turner Cc: Russell King Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib: reduce the use of module.h wherever possible

2012-03-07T20:04:04Z

For files only using THIS_MODULE and/or EXPORT_SYMBOL, map them onto including export.h -- or if the file isn't even using those, then just delete the include. Fix up any implicit include dependencies that were being masked by module.h along the way. Signed-off-by: Paul Gortmaker

vsprintf: make %pV handling compatible with kasprintf()

2012-03-06T16:22:26Z

kasprintf() (and potentially other functions that I didn't run across so far) want to evaluate argument lists twice. Caring to do so for the primary list is obviously their job, but they can't reasonably be expected to check the format string for instances of %pV, which however need special handling too: On architectures like x86-64 (as opposed to e.g. ix86), using the same argument list twice doesn't produce the expected results, as an internally managed cursor gets updated during the first run. Fix the problem by always acting on a copy of the original list when handling %pV. Signed-off-by: Jan Beulich Signed-off-by: Linus Torvalds

net: introduce and use netdev_features_t for device features sets

2011-11-16T22:43:10Z

v2: add couple missing conversions in drivers split unexporting netdev_fix_features() implemented %pNF convert sock::sk_route_(no?)caps Signed-off-by: Michał Mirosław Signed-off-by: David S. Miller

lib: rename pack_hex_byte() to hex_byte_pack()

2011-11-01T00:30:56Z

As suggested by Andrew Morton in [1] there is better to have most significant part first in the function name. [1] https://lkml.org/lkml/2011/9/20/22 There is no functional change. Signed-off-by: Andy Shevchenko Cc: Jesper Nilsson Cc: David Howells Cc: Koichi Yasutake Cc: Jason Wessel Cc: Mimi Zohar Cc: James Morris Cc: OGAWA Hirofumi Cc: "John W. Linville" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds