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| author | Yury Norov <yury.norov@gmail.com> | 2021-04-21 06:13:25 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-05-11 01:38:20 +0300 |
| commit | b18def121f077857ccf92fc620366e19850bc297 (patch) | |
| tree | b19cef760cf5a2e53c37633b6cfb365c75c6abac | |
| parent | 6efb943b8616ec53a5e444193dccf1af9ad627b5 (diff) | |
| download | linux-b18def121f077857ccf92fc620366e19850bc297.tar.xz | |
bitmap_parse: Support 'all' semantics
RCU code supports an 'all' group as a special case when parsing rcu_nocbs
parameter. This patch moves the 'all' support to the core bitmap_parse
code, so that all bitmap users can enjoy this extension.
Moving 'all' parsing to a bitmap_parse level also allows users to pass
patterns together with 'all' in regular group:pattern format, for example,
"rcu_nocbs=all:1/2" would offload all the even-numbered CPUs regardless
of the number of CPUs on the system.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.rst | 5 | ||||
| -rw-r--r-- | lib/bitmap.c | 9 | ||||
| -rw-r--r-- | lib/test_bitmap.c | 7 |
3 files changed, 21 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst index 3996b54158bf..01ba293a2d70 100644 --- a/Documentation/admin-guide/kernel-parameters.rst +++ b/Documentation/admin-guide/kernel-parameters.rst @@ -76,6 +76,11 @@ to change, such as less cores in the CPU list, then N and any ranges using N will also change. Use the same on a small 4 core system, and "16-N" becomes "16-3" and now the same boot input will be flagged as invalid (start > end). +The special case-tolerant group name "all" has a meaning of selecting all CPUs, +so that "nohz_full=all" is the equivalent of "nohz_full=0-N". + +The semantics of "N" and "all" is supported on a level of bitmaps and holds for +all users of bitmap_parse(). This document may not be entirely up to date and comprehensive. The command "modinfo -p ${modulename}" shows a current list of all parameters of a loadable diff --git a/lib/bitmap.c b/lib/bitmap.c index 74ceb02f45e3..6e29b2aae6ba 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -581,6 +581,14 @@ static const char *bitmap_parse_region(const char *str, struct region *r) { unsigned int lastbit = r->nbits - 1; + if (!strncasecmp(str, "all", 3)) { + r->start = 0; + r->end = lastbit; + str += 3; + + goto check_pattern; + } + str = bitmap_getnum(str, &r->start, lastbit); if (IS_ERR(str)) return str; @@ -595,6 +603,7 @@ static const char *bitmap_parse_region(const char *str, struct region *r) if (IS_ERR(str)) return str; +check_pattern: if (end_of_region(*str)) goto no_pattern; diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c index 9cd575583180..4ea73f5aed41 100644 --- a/lib/test_bitmap.c +++ b/lib/test_bitmap.c @@ -366,6 +366,13 @@ static const struct test_bitmap_parselist parselist_tests[] __initconst = { {0, "0-31:1/3,1-31:1/3,2-31:1/3", &exp1[8 * step], 32, 0}, {0, "1-10:8/12,8-31:24/29,0-31:0/3", &exp1[9 * step], 32, 0}, + {0, "all", &exp1[8 * step], 32, 0}, + {0, "0, 1, all, ", &exp1[8 * step], 32, 0}, + {0, "all:1/2", &exp1[4 * step], 32, 0}, + {0, "ALL:1/2", &exp1[4 * step], 32, 0}, + {-EINVAL, "al", NULL, 8, 0}, + {-EINVAL, "alll", NULL, 8, 0}, + {-EINVAL, "-1", NULL, 8, 0}, {-EINVAL, "-0", NULL, 8, 0}, {-EINVAL, "10-1", NULL, 8, 0}, |