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dhcp: binary search in nm_dhcp_option_find()

Browse source 
Let's use binary search.

Test patch:

    diff --git a/src/core/dhcp/tests/test-dhcp-utils.c b/src/core/dhcp/tests/test-dhcp-utils.c
    index 9b54e2cd0228..007993341672 100644
    --- a/src/core/dhcp/tests/test-dhcp-utils.c
    +++ b/src/core/dhcp/tests/test-dhcp-utils.c
    @@ -788,6 +788,24 @@ NMTST_DEFINE();
     int
     main(int argc, char **argv)
     {
    +    int i;
    +    guint idx;
    +    guint c;
    +
    +    idx = 0;
    +    c = 0;
    +    for (i = 0; i < 1000000; i++) {
    +        const guint option = _nm_dhcp_option_dhcp4_options[idx % G_N_ELEMENTS(_nm_dhcp_option_dhcp4_options)].option_num;
    +
    +        idx += 2010055757;
    +
    +        if (nm_dhcp_option_find(AF_INET, option)->name)
    +            c++;
    +    }
    +    g_print(">%u\n", c);
    +
    +    return 0;
    +
         nmtst_init_assert_logging(&argc, &argv, "WARN", "DEFAULT");

         g_test_add_func("/dhcp/generic-options", test_generic_options);

Build:

  CFLAGS='-O2' ./autogen.sh --with-more-asserts=0
  make -j 10 src/core/dhcp/tests/test-dhcp-utils && \
    src/core/dhcp/tests/test-dhcp-utils && \
    perf stat -r 200 -B src/core/dhcp/tests/test-dhcp-utils

Before:

 Performance counter stats for 'src/core/dhcp/tests/test-dhcp-utils' (200 runs):

             82.83 msec task-clock:u              #    0.994 CPUs utilized            ( +-  0.21% )
                 0      context-switches:u        #    0.000 K/sec
                 0      cpu-migrations:u          #    0.000 K/sec
               579      page-faults:u             #    0.007 M/sec                    ( +-  0.03% )
       264,676,245      cycles:u                  #    3.195 GHz                      ( +-  0.06% )
       544,792,266      instructions:u            #    2.06  insn per cycle           ( +-  0.00% )
       151,624,848      branches:u                # 1830.472 M/sec                    ( +-  0.00% )
         1,083,780      branch-misses:u           #    0.71% of all branches          ( +-  0.01% )

          0.083328 +- 0.000178 seconds time elapsed  ( +-  0.21% )

After:

 Performance counter stats for 'src/core/dhcp/tests/test-dhcp-utils' (200 runs):

             39.21 msec task-clock:u              #    0.987 CPUs utilized            ( +-  0.57% )
                 0      context-switches:u        #    0.000 K/sec
                 0      cpu-migrations:u          #    0.000 K/sec
               579      page-faults:u             #    0.015 M/sec                    ( +-  0.03% )
       115,396,123      cycles:u                  #    2.943 GHz                      ( +-  0.23% )
       137,664,630      instructions:u            #    1.19  insn per cycle           ( +-  0.00% )
        25,866,025      branches:u                #  659.597 M/sec                    ( +-  0.00% )
         1,919,616      branch-misses:u           #    7.42% of all branches          ( +-  0.12% )

          0.039717 +- 0.000227 seconds time elapsed  ( +-  0.57% )
This commit is contained in:
Thomas Haller 2021-02-11 11:36:44 +01:00
parent 1cbe926c20
commit 24abf13239
No known key found for this signature in database
GPG key ID: 29C2366E4DFC5728
1 changed files with 162 additions and 10 deletions
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172
src/core/dhcp/nm-dhcp-options.c
View file

@ -7,6 +7,8 @@
#include "nm-dhcp-options.h"
#include "nm-glib-aux/nm-str-buf.h"
/*****************************************************************************/
#define REQ(_num, _name, _include) \
@ -169,6 +171,23 @@ const NMDhcpOption _nm_dhcp_option_dhcp4_options[] = {
REQ(NM_DHCP_OPTION_DHCP4_NM_NEXT_SERVER, "next_server", FALSE),
};
static const NMDhcpOption *const _sorted_options_4[G_N_ELEMENTS(_nm_dhcp_option_dhcp4_options)] = {
#define A(idx) (&_nm_dhcp_option_dhcp4_options[(idx)])
A(0), A(1), A(8), A(18), A(19), A(2), A(20), A(21), A(22), A(23), A(24), A(3),
A(25), A(26), A(4), A(27), A(17), A(28), A(29), A(30), A(31), A(32), A(33), A(34),
A(35), A(5), A(36), A(6), A(37), A(38), A(39), A(40), A(9), A(41), A(42), A(43),
A(44), A(45), A(46), A(10), A(11), A(12), A(47), A(48), A(49), A(50), A(51), A(52),
A(13), A(53), A(54), A(55), A(57), A(58), A(59), A(60), A(61), A(62), A(63), A(64),
A(65), A(66), A(67), A(68), A(69), A(70), A(71), A(72), A(73), A(74), A(75), A(76),
A(77), A(78), A(79), A(80), A(81), A(82), A(83), A(84), A(85), A(86), A(87), A(56),
A(88), A(89), A(90), A(91), A(92), A(93), A(14), A(7), A(94), A(95), A(96), A(97),
A(98), A(99), A(100), A(101), A(102), A(103), A(104), A(105), A(106), A(107), A(108), A(109),
A(110), A(111), A(112), A(113), A(114), A(115), A(116), A(117), A(118), A(119), A(120), A(121),
A(122), A(123), A(124), A(125), A(126), A(127), A(128), A(129), A(130), A(131), A(132), A(133),
A(134), A(15), A(135), A(136), A(16), A(137), A(138), A(139), A(140), A(141),
#undef A
};
const NMDhcpOption _nm_dhcp_option_dhcp6_options[] = {
REQ(NM_DHCP_OPTION_DHCP6_CLIENTID, "dhcp6_client_id", FALSE),
@ -197,27 +216,160 @@ const NMDhcpOption _nm_dhcp_option_dhcp6_options[] = {
#undef REQ
static const NMDhcpOption *const _sorted_options_6[G_N_ELEMENTS(_nm_dhcp_option_dhcp6_options)] = {
#define A(idx) (&_nm_dhcp_option_dhcp6_options[(idx)])
A(0),
A(1),
A(2),
A(3),
A(4),
A(5),
A(6),
A(7),
A(8),
A(9),
A(10),
A(11),
A(12),
A(13),
A(14),
A(15),
#undef A
};
/*****************************************************************************/
static int
_sorted_options_generate_sort(gconstpointer pa, gconstpointer pb, gpointer user_data)
{
const NMDhcpOption *const *a = pa;
const NMDhcpOption *const *b = pb;
NM_CMP_DIRECT((*a)->option_num, (*b)->option_num);
return nm_assert_unreachable_val(0);
}
static char *
_sorted_options_generate(const NMDhcpOption *base, const NMDhcpOption *const *sorted, guint n)
{
gs_free const NMDhcpOption **sort2 = NULL;
NMStrBuf sbuf = NM_STR_BUF_INIT(0, FALSE);
guint i;
sort2 = nm_memdup(sorted, n * sizeof(sorted[0]));
g_qsort_with_data(sort2, n, sizeof(sort2[0]), _sorted_options_generate_sort, NULL);
for (i = 0; i < n; i++) {
if (i > 0)
nm_str_buf_append(&sbuf, ", ");
nm_str_buf_append_printf(&sbuf, "A(%d)", (int) (sort2[i] - base));
}
return nm_str_buf_finalize(&sbuf, NULL);
}
_nm_unused static void
_ASSERT_sorted(int IS_IPv4, const NMDhcpOption *const *const sorted, int n)
{
const NMDhcpOption *const options =
IS_IPv4 ? _nm_dhcp_option_dhcp4_options : _nm_dhcp_option_dhcp6_options;
int i;
int j;
gs_free char *sorted_msg = NULL;
for (i = 0; i < n; i++) {
const NMDhcpOption *opt = sorted[i];
g_assert(opt);
g_assert(opt >= options);
g_assert(opt < &options[n]);
for (j = 0; j < i; j++) {
const NMDhcpOption *opt2 = sorted[j];
if (opt == opt2) {
g_error("%s:%d: the _sorted_options_%c at [%d] (opt=%u, %s) is duplicated at "
"[%d] (SORT: %s)",
__FILE__,
__LINE__,
IS_IPv4 ? '4' : '6',
i,
opt->option_num,
opt->name,
j,
(sorted_msg = _sorted_options_generate(options, sorted, n)));
}
}
if (i > 0) {
const NMDhcpOption *opt2 = sorted[i - 1];
if (opt2->option_num >= opt->option_num) {
g_error("%s:%d: the _sorted_options_%c at [%d] (opt=%u, %s) should come before "
"[%d] (opt=%u, %s) (SORT: %s)",
__FILE__,
__LINE__,
IS_IPv4 ? '4' : '6',
i,
opt->option_num,
opt->name,
i - 1,
opt2->option_num,
opt2->name,
(sorted_msg = _sorted_options_generate(options, sorted, n)));
}
}
}
}
/*****************************************************************************/
const NMDhcpOption *
nm_dhcp_option_find(int addr_family, guint option)
{
const int IS_IPv4 = NM_IS_IPv4(addr_family);
const NMDhcpOption *const options =
IS_IPv4 ? _nm_dhcp_option_dhcp4_options : _nm_dhcp_option_dhcp6_options;
int n_options = IS_IPv4 ? G_N_ELEMENTS(_nm_dhcp_option_dhcp4_options)
: G_N_ELEMENTS(_nm_dhcp_option_dhcp6_options);
int i;
const int IS_IPv4 = NM_IS_IPv4(addr_family);
const NMDhcpOption *const *const sorted = IS_IPv4 ? _sorted_options_4 : _sorted_options_6;
const int n = IS_IPv4 ? G_N_ELEMENTS(_nm_dhcp_option_dhcp4_options)
: G_N_ELEMENTS(_nm_dhcp_option_dhcp6_options);
int imin = 0;
int imax = n - 1;
int imid = (n - 1) / 2;
for (i = 0; i < n_options; i++) {
const NMDhcpOption *opt = &options[i];
#if NM_MORE_ASSERTS > 10
nm_assert(n < G_MAXINT / 2);
if (IS_IPv4 && !NM_MORE_ASSERT_ONCE(10)) {
/* already checked */
} else if (!IS_IPv4 && !NM_MORE_ASSERT_ONCE(10)) {
/* already checked */
} else
_ASSERT_sorted(IS_IPv4, sorted, n);
#endif
if (opt->option_num == option)
return opt;
for (;;) {
const guint o = sorted[imid]->option_num;
if (G_UNLIKELY(o == option))
return sorted[imid];
if (o < option)
imin = imid + 1;
else
imax = imid - 1;
if (G_UNLIKELY(imin > imax))
break;
imid = (imin + imax) / 2;
}
/* Option should always be found */
return nm_assert_unreachable_val(NULL);
}
/*****************************************************************************/
void
nm_dhcp_option_take_option(GHashTable *options, int addr_family, guint option, char *value)
{