diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 50 | ||||
| -rw-r--r-- | lib/bitmap.c | 50 |
2 files changed, 82 insertions, 18 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 705fb915cbf7..a1489e14f8ee 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -33,6 +33,37 @@ can also be entered as Double-quotes can be used to protect spaces in values, e.g.: param="spaces in here" +cpu lists: +---------- + +Some kernel parameters take a list of CPUs as a value, e.g. isolcpus, +nohz_full, irqaffinity, rcu_nocbs. The format of this list is: + + <cpu number>,...,<cpu number> + +or + + <cpu number>-<cpu number> + (must be a positive range in ascending order) + +or a mixture + +<cpu number>,...,<cpu number>-<cpu number> + +Note that for the special case of a range one can split the range into equal +sized groups and for each group use some amount from the beginning of that +group: + + <cpu number>-cpu number>:<used size>/<group size> + +For example one can add to the command line following parameter: + + isolcpus=1,2,10-20,100-2000:2/25 + +where the final item represents CPUs 100,101,125,126,150,151,... + + + 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 module. Loadable modules, after being loaded into the running kernel, also @@ -1789,13 +1820,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. See Documentation/filesystems/nfs/nfsroot.txt. irqaffinity= [SMP] Set the default irq affinity mask - Format: - <cpu number>,...,<cpu number> - or - <cpu number>-<cpu number> - (must be a positive range in ascending order) - or a mixture - <cpu number>,...,<cpu number>-<cpu number> + The argument is a cpu list, as described above. irqfixup [HW] When an interrupt is not handled search all handlers @@ -1812,13 +1837,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Format: <RDP>,<reset>,<pci_scan>,<verbosity> isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. - Format: - <cpu number>,...,<cpu number> - or - <cpu number>-<cpu number> - (must be a positive range in ascending order) - or a mixture - <cpu number>,...,<cpu number>-<cpu number> + The argument is a cpu list, as described above. This option can be used to specify one or more CPUs to isolate from the general SMP balancing and scheduling @@ -2680,6 +2699,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Default: on nohz_full= [KNL,BOOT] + The argument is a cpu list, as described above. In kernels built with CONFIG_NO_HZ_FULL=y, set the specified list of CPUs whose tick will be stopped whenever possible. The boot CPU will be forced outside @@ -3285,6 +3305,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. See Documentation/blockdev/ramdisk.txt. rcu_nocbs= [KNL] + The argument is a cpu list, as described above. + In kernels built with CONFIG_RCU_NOCB_CPU=y, set the specified list of CPUs to be no-callback CPUs. Invocation of these CPUs' RCU callbacks will diff --git a/lib/bitmap.c b/lib/bitmap.c index eca88087fa8a..0b66f0e5eb6b 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -496,6 +496,11 @@ EXPORT_SYMBOL(bitmap_print_to_pagebuf); * ranges. Consecutively set bits are shown as two hyphen-separated * decimal numbers, the smallest and largest bit numbers set in * the range. + * Optionally each range can be postfixed to denote that only parts of it + * should be set. The range will divided to groups of specific size. + * From each group will be used only defined amount of bits. + * Syntax: range:used_size/group_size + * Example: 0-1023:2/256 ==> 0,1,256,257,512,513,768,769 * * Returns 0 on success, -errno on invalid input strings. * Error values: @@ -507,16 +512,20 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen, int is_user, unsigned long *maskp, int nmaskbits) { - unsigned a, b; + unsigned int a, b, old_a, old_b; + unsigned int group_size, used_size; int c, old_c, totaldigits, ndigits; const char __user __force *ubuf = (const char __user __force *)buf; - int at_start, in_range; + int at_start, in_range, in_partial_range; totaldigits = c = 0; + old_a = old_b = 0; + group_size = used_size = 0; bitmap_zero(maskp, nmaskbits); do { at_start = 1; in_range = 0; + in_partial_range = 0; a = b = 0; ndigits = totaldigits; @@ -547,6 +556,24 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen, if ((totaldigits != ndigits) && isspace(old_c)) return -EINVAL; + if (c == '/') { + used_size = a; + at_start = 1; + in_range = 0; + a = b = 0; + continue; + } + + if (c == ':') { + old_a = a; + old_b = b; + at_start = 1; + in_range = 0; + in_partial_range = 1; + a = b = 0; + continue; + } + if (c == '-') { if (at_start || in_range) return -EINVAL; @@ -567,15 +594,30 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen, } if (ndigits == totaldigits) continue; + if (in_partial_range) { + group_size = a; + a = old_a; + b = old_b; + old_a = old_b = 0; + } /* if no digit is after '-', it's wrong*/ if (at_start && in_range) return -EINVAL; - if (!(a <= b)) + if (!(a <= b) || !(used_size <= group_size)) return -EINVAL; if (b >= nmaskbits) return -ERANGE; while (a <= b) { - set_bit(a, maskp); + if (in_partial_range) { + static int pos_in_group = 1; + + if (pos_in_group <= used_size) + set_bit(a, maskp); + + if (a == b || ++pos_in_group > group_size) + pos_in_group = 1; + } else + set_bit(a, maskp); a++; } } while (buflen && c == ','); |