Messages in this thread | | | Subject | Re: [PATCH v3] lib/bitmap.c: enhance bitmap syntax | From | Pan Xinhui <> | Date | Sun, 17 Jul 2016 21:59:21 +0800 |
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在 16/7/17 21:50, Pan Xinhui 写道: > > > 在 16/7/17 16:10, Noam Camus 写道: >> From: Noam Camus <noamca@mellanox.com> >> >> Today there are platforms with many CPUs (up to 4K). >> Trying to boot only part of the CPUs may result in too long string. >> >> For example lets take NPS platform that is part of arch/arc. >> This platform have SMP system with 256 cores each with >> 16 HW threads (SMT machine) where HW thread appears as CPU to the kernel. >> In this example there is total of 4K CPUs. >> When one tries to boot only part of the HW threads from each core the >> string representing the map may be long... >> For example if for sake of performance we decided to boot only first half >> of HW threads of each core the map will look like: >> 0-7,16-23,32-39,...,4080-4087 >> >> This patch introduce new syntax to accommodate with such use case. >> I added an optional postfix to a range of CPUs which will choose >> according to given modulo the desired range of reminders i.e.: >> <cpus range>%modulo=<range of reminders> >> >> For example, above map can be described in new syntax like this: >> 0-4095%16=0-7 >> > > I really think it is better to implement one function to generic a string which contanis the cpus you want to boot on, then pass this string to __bitmap_parselist. > sorry, typos. generic -> generate.
>> Note that this patch is backward compatible with current syntax. >> >> Signed-off-by: Noam Camus <noamca@mellanox.com> >> --- >> Any sugestions for simpler syntax which keeps its generality are welcomed. >> >> Change Log: >> V2: Fix typo in example at function header for __bitmap_parselist() >> V3: Fix typo in commit log and also typo at example >> --- >> lib/bitmap.c | 44 ++++++++++++++++++++++++++++++++++++++++---- >> 1 files changed, 40 insertions(+), 4 deletions(-) >> >> diff --git a/lib/bitmap.c b/lib/bitmap.c >> index c66da50..bccfd87 100644 >> --- a/lib/bitmap.c >> +++ b/lib/bitmap.c >> @@ -496,6 +496,9 @@ 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 parts are the range of reminders modulo some value. >> + * i.e. range%mod=rem_range e.g. 0-1023%256=0-1 ==> 0,1,256,257,512,513,768,769 >> * >> * Returns 0 on success, -errno on invalid input strings. >> * Error values: >> @@ -507,12 +510,14 @@ 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, mod_val, mod_a, mod_b; >> int c, old_c, totaldigits, ndigits; >> const char __user __force *ubuf = (const char __user __force *)buf; >> int at_start, in_range; >> >> totaldigits = c = 0; >> + old_a = old_b = 0; >> + mod_val = mod_a = mod_b = 0; >> bitmap_zero(maskp, nmaskbits); >> do { >> at_start = 1; >> @@ -547,6 +552,23 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen, >> if ((totaldigits != ndigits) && isspace(old_c)) >> return -EINVAL; >> >> + if (c == '=') { >> + mod_val = 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; >> + a = b = 0; >> + continue; >> + } >> + >> if (c == '-') { >> if (at_start || in_range) >> return -EINVAL; >> @@ -567,17 +589,31 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen, >> } >> if (ndigits == totaldigits) >> continue; >> + if (mod_val) { >> + mod_a = a; >> + mod_b = b; >> + 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) || !(mod_a <= mod_b)) >> return -EINVAL; >> - if (b >= nmaskbits) >> + if (b >= nmaskbits || (mod_val && (mod_b >= mod_val))) >> return -ERANGE; >> while (a <= b) { >> - set_bit(a, maskp); >> + if (mod_val) { >> + unsigned int rem = a % mod_val; >> + >> + if (rem >= mod_a && rem <= mod_b) >> + set_bit(a, maskp); >> + } else >> + set_bit(a, maskp); >> a++; >> } >> + mod_val = mod_a = mod_b = 0; >> } while (buflen && c == ','); >> return 0; >> } >>
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