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author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-07-25 13:20:41 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-07-25 13:20:41 -0700 |
commit | 7e4dc77b2869a683fc43c0394fca5441816390ba (patch) | |
tree | 62e734c599bc1da2712fdb63be996622c415a83a /tools/include/linux/hash.h | |
parent | Merge branch 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (diff) | |
parent | Merge tag 'perf-core-for-mingo-20160718' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core (diff) | |
download | linux-dev-7e4dc77b2869a683fc43c0394fca5441816390ba.tar.xz linux-dev-7e4dc77b2869a683fc43c0394fca5441816390ba.zip |
Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf updates from Ingo Molnar:
"With over 300 commits it's been a busy cycle - with most of the work
concentrated on the tooling side (as it should).
The main kernel side enhancements were:
- Add per event callchain limit: Recently we introduced a sysctl to
tune the max-stack for all events for which callchains were
requested:
$ sysctl kernel.perf_event_max_stack
kernel.perf_event_max_stack = 127
Now this patch introduces a way to configure this per event, i.e.
this becomes possible:
$ perf record -e sched:*/max-stack=2/ -e block:*/max-stack=10/ -a
allowing finer tuning of how much buffer space callchains use.
This uses an u16 from the reserved space at the end, leaving
another u16 for future use.
There has been interest in even finer tuning, namely to control the
max stack for kernel and userspace callchains separately. Further
discussion is needed, we may for instance use the remaining u16 for
that and when it is present, assume that the sample_max_stack
introduced in this patch applies for the kernel, and the u16 left
is used for limiting the userspace callchain (Arnaldo Carvalho de
Melo)
- Optimize AUX event (hardware assisted side-band event) delivery
(Kan Liang)
- Rework Intel family name macro usage (this is partially x86 arch
work) (Dave Hansen)
- Refine and fix Intel LBR support (David Carrillo-Cisneros)
- Add support for Intel 'TopDown' events (Andi Kleen)
- Intel uncore PMU driver fixes and enhancements (Kan Liang)
- ... other misc changes.
Here's an incomplete list of the tooling enhancements (but there's
much more, see the shortlog and the git log for details):
- Support cross unwinding, i.e. collecting '--call-graph dwarf'
perf.data files in one machine and then doing analysis in another
machine of a different hardware architecture. This enables, for
instance, to do:
$ perf record -a --call-graph dwarf
on a x86-32 or aarch64 system and then do 'perf report' on it on a
x86_64 workstation (He Kuang)
- Allow reading from a backward ring buffer (one setup via
sys_perf_event_open() with perf_event_attr.write_backward = 1)
(Wang Nan)
- Finish merging initial SDT (Statically Defined Traces) support, see
cset comments for details about how it all works (Masami Hiramatsu)
- Support attaching eBPF programs to tracepoints (Wang Nan)
- Add demangling of symbols in programs written in the Rust language
(David Tolnay)
- Add support for tracepoints in the python binding, including an
example, that sets up and parses sched:sched_switch events,
tools/perf/python/tracepoint.py (Jiri Olsa)
- Introduce --stdio-color to set up the color output mode selection
in 'annotate' and 'report', allowing emit color escape sequences
when redirecting the output of these tools (Arnaldo Carvalho de
Melo)
- Add 'callindent' option to 'perf script -F', to indent the Intel PT
call stack, making this output more ftrace-like (Adrian Hunter,
Andi Kleen)
- Allow dumping the object files generated by llvm when processing
eBPF scriptlet events (Wang Nan)
- Add stackcollapse.py script to help generating flame graphs (Paolo
Bonzini)
- Add --ldlat option to 'perf mem' to specify load latency for loads
event (e.g. cpu/mem-loads/ ) (Jiri Olsa)
- Tooling support for Intel TopDown counters, recently added to the
kernel (Andi Kleen)"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (303 commits)
perf tests: Add is_printable_array test
perf tools: Make is_printable_array global
perf script python: Fix string vs byte array resolving
perf probe: Warn unmatched function filter correctly
perf cpu_map: Add more helpers
perf stat: Balance opening and reading events
tools: Copy linux/{hash,poison}.h and check for drift
perf tools: Remove include/linux/list.h from perf's MANIFEST
tools: Copy the bitops files accessed from the kernel and check for drift
Remove: kernel unistd*h files from perf's MANIFEST, not used
perf tools: Remove tools/perf/util/include/linux/const.h
perf tools: Remove tools/perf/util/include/asm/byteorder.h
perf tools: Add missing linux/compiler.h include to perf-sys.h
perf jit: Remove some no-op error handling
perf jit: Add missing curly braces
objtool: Initialize variable to silence old compiler
objtool: Add -I$(srctree)/tools/arch/$(ARCH)/include/uapi
perf record: Add --tail-synthesize option
perf session: Don't warn about out of order event if write_backward is used
perf tools: Enable overwrite settings
...
Diffstat (limited to 'tools/include/linux/hash.h')
-rw-r--r-- | tools/include/linux/hash.h | 105 |
1 files changed, 102 insertions, 3 deletions
diff --git a/tools/include/linux/hash.h b/tools/include/linux/hash.h index d026c6573018..ad6fa21d977b 100644 --- a/tools/include/linux/hash.h +++ b/tools/include/linux/hash.h @@ -1,5 +1,104 @@ -#include "../../../include/linux/hash.h" +#ifndef _LINUX_HASH_H +#define _LINUX_HASH_H +/* Fast hashing routine for ints, longs and pointers. + (C) 2002 Nadia Yvette Chambers, IBM */ -#ifndef _TOOLS_LINUX_HASH_H -#define _TOOLS_LINUX_HASH_H +#include <asm/types.h> +#include <linux/compiler.h> + +/* + * The "GOLDEN_RATIO_PRIME" is used in ifs/btrfs/brtfs_inode.h and + * fs/inode.c. It's not actually prime any more (the previous primes + * were actively bad for hashing), but the name remains. + */ +#if BITS_PER_LONG == 32 +#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_32 +#define hash_long(val, bits) hash_32(val, bits) +#elif BITS_PER_LONG == 64 +#define hash_long(val, bits) hash_64(val, bits) +#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_64 +#else +#error Wordsize not 32 or 64 +#endif + +/* + * This hash multiplies the input by a large odd number and takes the + * high bits. Since multiplication propagates changes to the most + * significant end only, it is essential that the high bits of the + * product be used for the hash value. + * + * Chuck Lever verified the effectiveness of this technique: + * http://www.citi.umich.edu/techreports/reports/citi-tr-00-1.pdf + * + * Although a random odd number will do, it turns out that the golden + * ratio phi = (sqrt(5)-1)/2, or its negative, has particularly nice + * properties. (See Knuth vol 3, section 6.4, exercise 9.) + * + * These are the negative, (1 - phi) = phi**2 = (3 - sqrt(5))/2, + * which is very slightly easier to multiply by and makes no + * difference to the hash distribution. + */ +#define GOLDEN_RATIO_32 0x61C88647 +#define GOLDEN_RATIO_64 0x61C8864680B583EBull + +#ifdef CONFIG_HAVE_ARCH_HASH +/* This header may use the GOLDEN_RATIO_xx constants */ +#include <asm/hash.h> +#endif + +/* + * The _generic versions exist only so lib/test_hash.c can compare + * the arch-optimized versions with the generic. + * + * Note that if you change these, any <asm/hash.h> that aren't updated + * to match need to have their HAVE_ARCH_* define values updated so the + * self-test will not false-positive. + */ +#ifndef HAVE_ARCH__HASH_32 +#define __hash_32 __hash_32_generic +#endif +static inline u32 __hash_32_generic(u32 val) +{ + return val * GOLDEN_RATIO_32; +} + +#ifndef HAVE_ARCH_HASH_32 +#define hash_32 hash_32_generic #endif +static inline u32 hash_32_generic(u32 val, unsigned int bits) +{ + /* High bits are more random, so use them. */ + return __hash_32(val) >> (32 - bits); +} + +#ifndef HAVE_ARCH_HASH_64 +#define hash_64 hash_64_generic +#endif +static __always_inline u32 hash_64_generic(u64 val, unsigned int bits) +{ +#if BITS_PER_LONG == 64 + /* 64x64-bit multiply is efficient on all 64-bit processors */ + return val * GOLDEN_RATIO_64 >> (64 - bits); +#else + /* Hash 64 bits using only 32x32-bit multiply. */ + return hash_32((u32)val ^ __hash_32(val >> 32), bits); +#endif +} + +static inline u32 hash_ptr(const void *ptr, unsigned int bits) +{ + return hash_long((unsigned long)ptr, bits); +} + +/* This really should be called fold32_ptr; it does no hashing to speak of. */ +static inline u32 hash32_ptr(const void *ptr) +{ + unsigned long val = (unsigned long)ptr; + +#if BITS_PER_LONG == 64 + val ^= (val >> 32); +#endif + return (u32)val; +} + +#endif /* _LINUX_HASH_H */ |