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author | Yury Norov <yury.norov@gmail.com> | 2021-08-14 14:17:13 -0700 |
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committer | Yury Norov <yury.norov@gmail.com> | 2022-01-15 08:47:31 -0800 |
commit | 15325b4f768f2b27b5765489eeab6ec0d6b5e902 (patch) | |
tree | f29491038480dcf4575c84207f8f7ad2557f21d6 /lib | |
parent | db7313005e9c2d4e80888dd18d4a83926b920e8c (diff) | |
download | linux-15325b4f768f2b27b5765489eeab6ec0d6b5e902.tar.gz linux-15325b4f768f2b27b5765489eeab6ec0d6b5e902.tar.bz2 linux-15325b4f768f2b27b5765489eeab6ec0d6b5e902.zip |
vsprintf: rework bitmap_list_string
bitmap_list_string() is very ineffective when printing bitmaps with long
ranges of set bits because it calls find_next_bit for each bit in the
bitmap. We can do better by detecting ranges of set bits.
In my environment, before/after is 943008/31008 ns.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Diffstat (limited to 'lib')
-rw-r--r-- | lib/vsprintf.c | 24 |
1 files changed, 7 insertions, 17 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 58d5e567f836..d4b4e481045b 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1241,20 +1241,13 @@ char *bitmap_list_string(char *buf, char *end, unsigned long *bitmap, struct printf_spec spec, const char *fmt) { int nr_bits = max_t(int, spec.field_width, 0); - /* current bit is 'cur', most recently seen range is [rbot, rtop] */ - int cur, rbot, rtop; bool first = true; + int rbot, rtop; if (check_pointer(&buf, end, bitmap, spec)) return buf; - rbot = cur = find_first_bit(bitmap, nr_bits); - while (cur < nr_bits) { - rtop = cur; - cur = find_next_bit(bitmap, nr_bits, cur + 1); - if (cur < nr_bits && cur <= rtop + 1) - continue; - + for_each_set_bitrange(rbot, rtop, bitmap, nr_bits) { if (!first) { if (buf < end) *buf = ','; @@ -1263,15 +1256,12 @@ char *bitmap_list_string(char *buf, char *end, unsigned long *bitmap, first = false; buf = number(buf, end, rbot, default_dec_spec); - if (rbot < rtop) { - if (buf < end) - *buf = '-'; - buf++; - - buf = number(buf, end, rtop, default_dec_spec); - } + if (rtop == rbot + 1) + continue; - rbot = cur; + if (buf < end) + *buf = '-'; + buf = number(++buf, end, rtop - 1, default_dec_spec); } return buf; } |