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resolv: Optimize inet_ntop
The benchtests/inet_ntop_ipv4 and benchtests/inet_ntop_ipv6 profile
shows that most of time is spent in costly sprint operations:
$ perf record ./benchtests/bench-inet_ntop_ipv4 && perf report --stdio
[...]
38.53% bench-inet_ntop libc.so [.] __printf_buffer
18.69% bench-inet_ntop libc.so [.] __printf_buffer_write
11.01% bench-inet_ntop libc.so [.] _itoa_word
8.02% bench-inet_ntop bench-inet_ntop_ipv4 [.] bench_start
6.99% bench-inet_ntop libc.so [.] __memmove_avx_unaligned_erms
3.86% bench-inet_ntop libc.so [.] __strchrnul_avx2
2.82% bench-inet_ntop libc.so [.] __strcpy_avx2
1.90% bench-inet_ntop libc.so [.] inet_ntop4
1.78% bench-inet_ntop libc.so [.] __vsprintf_internal
1.55% bench-inet_ntop libc.so [.] __sprintf_chk
1.18% bench-inet_ntop libc.so [.] __GI___inet_ntop
$ perf record ./benchtests/bench-inet_ntop_ipv6 && perf report --stdio
35.44% bench-inet_ntop libc.so [.] __printf_buffer
14.35% bench-inet_ntop libc.so [.] __printf_buffer_write
10.27% bench-inet_ntop libc.so [.] __GI___inet_ntop
7.93% bench-inet_ntop libc.so [.] _itoa_word
7.00% bench-inet_ntop libc.so [.] __sprintf_chk
6.20% bench-inet_ntop libc.so [.] __vsprintf_internal
5.26% bench-inet_ntop libc.so [.] __strchrnul_avx2
5.05% bench-inet_ntop bench-inet_ntop_ipv6 [.] bench_start
3.70% bench-inet_ntop libc.so [.] __memmove_avx_unaligned_erms
2.11% bench-inet_ntop libc.so [.] __printf_buffer_done
A new implementation is used instead:
* The printf usage is replaced with an expanded function that prints
either an IPv4 octet or an IPv6 quartet;
* The strcpy is replaced with a memcpy (since ABIs usually tends to
optimize the latter);
* For IPv6, the '::' shorthanding is done in-place instead of using
a temporary buffer.
* An temporary buffer is used iff the size if larger than
INET_ADDRSTRLEN/INET6_ADDRSTRLEN.
* Inline is used for both inet_ntop4 and inet_ntop6,
The code is significand rewrote, so I take this requires a new license.
The performance results on aarch64 Neoverse1 with gcc 14.2.1:
* master
aarch64-linux-gnu-master$ ./benchtests/bench-inet_ntop_ipv4
"inet_ntop_ipv4": {
"workload-ipv4-random": {
"duration": 1.43067e+09,
"iterations": 8e+06,
"reciprocal-throughput": 178.572,
"latency": 179.096,
"max-throughput": 5.59997e+06,
"min-throughput": 5.58359e+06
}
aarch64-linux-gnu-master$ ./benchtests/bench-inet_ntop_ipv6
"inet_ntop_ipv6": {
"workload-ipv6-random": {
"duration": 1.68539e+09,
"iterations": 4e+06,
"reciprocal-throughput": 421.307,
"latency": 421.388,
"max-throughput": 2.37357e+06,
"min-throughput": 2.37311e+06
}
}
* patched
aarch64-linux-gnu$ ./benchtests/bench-inet_ntop_ipv4
"inet_ntop_ipv4": {
"workload-ipv4-random": {
"duration": 1.06133e+09,
"iterations": 5.6e+07,
"reciprocal-throughput": 18.8482,
"latency": 19.0565,
"max-throughput": 5.30555e+07,
"min-throughput": 5.24755e+07
}
}
aarch64-linux-gnu$ ./benchtests/bench-inet_ntop_ipv6
"inet_ntop_ipv6": {
"workload-ipv6-random": {
"duration": 1.01246e+09,
"iterations": 2.4e+07,
"reciprocal-throughput": 42.5576,
"latency": 41.8139,
"max-throughput": 2.34976e+07,
"min-throughput": 2.39155e+07
}
}
Checked on aarch64-linux-gnu and x86_64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
This commit is contained in:
Adhemerval Zanella
@@ -1,136 +1,155 @@
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/*
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* Copyright (c) 1996-1999 by Internet Software Consortium.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
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* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
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* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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/* Convert IPv4/IPv6 addresses from binary to text form.
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Copyright (C) 1996-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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#include <sys/param.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <arpa/nameser.h>
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#include <errno.h>
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#include <stdio.h>
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#include <string.h>
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#include <_itoa.h>
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#ifdef SPRINTF_CHAR
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# define SPRINTF(x) strlen (sprintf /**/ x)
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#else
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# define SPRINTF(x) ((size_t) sprintf x)
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#endif
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/*
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* WARNING: Don't even consider trying to compile this on a system where
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* sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
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*/
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static const char *inet_ntop4 (const u_char *src, char *dst, socklen_t size);
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static const char *inet_ntop6 (const u_char *src, char *dst, socklen_t size);
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/* char *
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* __inet_ntop(af, src, dst, size)
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* convert a network format address to presentation format.
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* return:
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* pointer to presentation format address (`dst'), or NULL (see errno).
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* author:
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* Paul Vixie, 1996.
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*/
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const char *
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__inet_ntop (int af, const void *src, char *dst, socklen_t size)
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static inline char *
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put_uint8 (uint8_t word, char *tp)
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{
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switch (af)
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int s = 1;
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if (word >= 10)
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{
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case AF_INET:
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return (inet_ntop4 (src, dst, size));
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case AF_INET6:
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return (inet_ntop6 (src, dst, size));
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default:
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__set_errno (EAFNOSUPPORT);
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return (NULL);
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if (word >= 100)
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{
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tp[2] = '0' + word % 10;
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word /= 10;
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s += 1;
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}
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tp[1] = '0' + word % 10;
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word /= 10;
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s += 1;
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}
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/* NOTREACHED */
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*tp = '0' + word;
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return tp + s;
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}
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libc_hidden_def (__inet_ntop)
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weak_alias (__inet_ntop, inet_ntop)
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/* const char *
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* inet_ntop4(src, dst, size)
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* format an IPv4 address
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* return:
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* `dst' (as a const)
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* notes:
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* (1) uses no statics
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* (2) takes a u_char* not an in_addr as input
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* author:
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* Paul Vixie, 1996.
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*/
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static const char *
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inet_ntop4 (const u_char *src, char *dst, socklen_t size)
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static inline char *
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put_uint16 (uint16_t word, char *tp)
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{
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static const char fmt[] = "%u.%u.%u.%u";
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char tmp[sizeof "255.255.255.255"];
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if (word >= 0x1000)
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*tp++ = _itoa_lower_digits[(word >> 12) & 0xf];
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if (word >= 0x100)
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*tp++ = _itoa_lower_digits[(word >> 8) & 0xf];
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if (word >= 0x10)
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*tp++ = _itoa_lower_digits[(word >> 4) & 0xf];
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*tp++ = _itoa_lower_digits[word & 0xf];
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return tp;
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}
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if (SPRINTF ((tmp, fmt, src[0], src[1], src[2], src[3])) >= size)
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static __always_inline char *
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inet_ntop4_format (const uint8_t *src, char *dst)
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{
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dst = put_uint8 (src[0], dst);
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*(dst++) = '.';
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dst = put_uint8 (src[1], dst);
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*(dst++) = '.';
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dst = put_uint8 (src[2], dst);
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*(dst++) = '.';
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dst = put_uint8 (src[3], dst);
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*dst++ = '\0';
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return dst;
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}
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static __always_inline const char *
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inet_ntop4 (const uint8_t *src, char *dst, socklen_t size)
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{
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if (size >= INET_ADDRSTRLEN)
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{
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inet_ntop4_format (src, dst);
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return dst;
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}
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char tmp[INET_ADDRSTRLEN];
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char *tp = inet_ntop4_format (src, tmp);
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socklen_t tmp_s = tp - tmp;
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if (tmp_s > size)
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{
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__set_errno (ENOSPC);
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return (NULL);
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return NULL;
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}
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return strcpy (dst, tmp);
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return memcpy (dst, tmp, tmp_s);
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}
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/* const char *
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* inet_ntop6(src, dst, size)
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* convert IPv6 binary address into presentation (printable) format
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* author:
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* Paul Vixie, 1996.
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*/
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static const char *
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inet_ntop6 (const u_char *src, char *dst, socklen_t size)
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struct best_t
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{
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/*
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* Note that int32_t and int16_t need only be "at least" large enough
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* to contain a value of the specified size. On some systems, like
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* Crays, there is no such thing as an integer variable with 16 bits.
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* Keep this in mind if you think this function should have been coded
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* to use pointer overlays. All the world's not a VAX.
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*/
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char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
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struct
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{
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int base, len;
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} best, cur;
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u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
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int i;
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int base;
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int len;
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};
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/*
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* Preprocess:
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* Copy the input (bytewise) array into a wordwise array.
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* Find the longest run of 0x00's in src[] for :: shorthanding.
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*/
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memset (words, '\0', sizeof words);
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for (i = 0; i < NS_IN6ADDRSZ; i += 2)
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words[i / 2] = (src[i] << 8) | src[i + 1];
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best.base = -1;
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cur.base = -1;
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best.len = 0;
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cur.len = 0;
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for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
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static inline uint16_t
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in6_addr_addr16 (const struct in6_addr *src, int idx)
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{
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const struct { uint16_t x; } __attribute__((__packed__)) *pptr =
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(typeof(pptr))(&src->s6_addr16[idx]);
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return ntohs (pptr->x);
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}
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static __always_inline char *
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inet_ntop6_format (const struct in6_addr *src, struct best_t best, char *dst)
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{
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char *tp = dst;
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for (int i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
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{
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if (words[i] == 0)
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/* Are we inside the best run of 0x00's? */
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if (best.base != -1 && i >= best.base && i < (best.base + best.len))
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{
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if (i == best.base)
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*tp++ = ':';
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continue;
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}
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/* Are we following an initial run of 0x00s or any real hex? */
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if (i != 0)
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*tp++ = ':';
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/* Is this address an encapsulated IPv4? */
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if (i == 6 && best.base == 0
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&& (best.len == 6 || (best.len == 5
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&& in6_addr_addr16 (src, 5) == 0xffff)))
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{
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if (!inet_ntop4 (src->s6_addr + 12, tp,
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INET6_ADDRSTRLEN - (tp - dst)))
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return NULL;
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tp += strlen (tp);
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break;
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}
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tp = put_uint16 (in6_addr_addr16 (src, i), tp);
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}
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/* Was it a trailing run of 0x00's? */
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if (best.base != -1 && (best.base + best.len) == (NS_IN6ADDRSZ / NS_INT16SZ))
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*tp++ = ':';
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*tp++ = '\0';
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return tp;
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}
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static inline const char *
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inet_ntop6 (const struct in6_addr *src, char *dst, socklen_t size)
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{
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struct best_t best = { -1, 0 }, cur = { -1, 0 };
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/* ind the longest run of 0x00's in src[] for :: shorthanding. */
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for (int i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
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{
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if (in6_addr_addr16 (src, i) == 0)
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{
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if (cur.base == -1)
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cur.base = i, cur.len = 1;
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@@ -155,45 +174,37 @@ inet_ntop6 (const u_char *src, char *dst, socklen_t size)
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if (best.base != -1 && best.len < 2)
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best.base = -1;
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/*
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* Format the result.
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*/
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tp = tmp;
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for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
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if (size >= INET6_ADDRSTRLEN)
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{
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/* Are we inside the best run of 0x00's? */
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if (best.base != -1 && i >= best.base && i < (best.base + best.len))
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{
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if (i == best.base)
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*tp++ = ':';
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continue;
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}
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/* Are we following an initial run of 0x00s or any real hex? */
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if (i != 0)
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*tp++ = ':';
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/* Is this address an encapsulated IPv4? */
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if (i == 6 && best.base == 0
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&& (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
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{
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if (!inet_ntop4 (src + 12, tp, sizeof tmp - (tp - tmp)))
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return (NULL);
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tp += strlen (tp);
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break;
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}
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tp += SPRINTF ((tp, "%x", words[i]));
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inet_ntop6_format (src, best, dst);
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return dst;
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}
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/* Was it a trailing run of 0x00's? */
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if (best.base != -1 && (best.base + best.len) == (NS_IN6ADDRSZ / NS_INT16SZ))
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*tp++ = ':';
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*tp++ = '\0';
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/*
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* Check for overflow, copy, and we're done.
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*/
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if ((socklen_t) (tp - tmp) > size)
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char tmp[INET6_ADDRSTRLEN];
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char *tp = inet_ntop6_format (src, best, tmp);
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socklen_t tmp_s = tp - tmp;
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if (tmp_s > size)
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{
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__set_errno (ENOSPC);
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return (NULL);
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}
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return strcpy (dst, tmp);
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return memcpy (dst, tmp, tmp_s);
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}
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const char *
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__inet_ntop (int af, const void *src, char *dst, socklen_t size)
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{
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switch (af)
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{
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case AF_INET:
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return (inet_ntop4 (src, dst, size));
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case AF_INET6:
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return (inet_ntop6 (src, dst, size));
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default:
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__set_errno (EAFNOSUPPORT);
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return (NULL);
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}
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}
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libc_hidden_def (__inet_ntop)
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weak_alias (__inet_ntop, inet_ntop)
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Reference in New Issue
Block a user