The patch titled
Subject: vsprintf: rework bitmap_list_string
has been added to the -mm tree. Its filename is
vsprintf-rework-bitmap_list_string.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/vsprintf-rework-bitmap_list_string.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/vsprintf-rework-bitmap_list_string.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Yury Norov <yury.norov@xxxxxxxxx>
Subject: 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.
Link: https://lkml.kernel.org/r/20210814211713.180533-18-yury.norov@xxxxxxxxx
Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
Tested-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Cc: Alexander Lobakin <alobakin@xxxxx>
Cc: Alexey Klimov <aklimov@xxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Dennis Zhou <dennis@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: kernel test robot <lkp@xxxxxxxxx>
Cc: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/vsprintf.c | 24 +++++++-----------------
1 file changed, 7 insertions(+), 17 deletions(-)
--- a/lib/vsprintf.c~vsprintf-rework-bitmap_list_string
+++ a/lib/vsprintf.c
@@ -1241,20 +1241,13 @@ char *bitmap_list_string(char *buf, char
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
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;
}
_
Patches currently in -mm which might be from yury.norov@xxxxxxxxx are
bitops-protect-find_first_zero_bit-properly.patch
bitops-move-find_bit__le-functions-from-leh-to-findh.patch
include-move-findh-from-asm_generic-to-linux.patch
arch-remove-generic_find_first_bit-entirely.patch
lib-add-find_first_and_bit.patch
cpumask-use-find_first_and_bit.patch
all-replace-find_next_zero_bit-with-find_first_zero_bit-where-appropriate.patch
tools-sync-tools-bitmap-with-mother-linux.patch
cpumask-replace-cpumask_next_-with-cpumask_first_-where-appropriate.patch
include-linux-move-for_each_bit-macros-from-bitopsh-to-findh.patch
find-micro-optimize-for_each_setclear_bit.patch
replace-for_each__bit_from-with-for_each__bit-where-appropriate.patch
mm-percpu-micro-optimize-pcpu_is_populated.patch
bitmap-unify-find_bit-operations.patch
lib-bitmap-add-performance-test-for-bitmap_print_to_pagebuf.patch
vsprintf-rework-bitmap_list_string.patch
